Tomdhu, I would just like add my thanks to the growing appreciative comments above, for your carefully worded and fascinating insights into this subject. Threads and sub-threads on this forum about the demise of the British truck industry are legion, and the theme of ‘missed opportunity’ seems to run through them all, alas. Yours appears to be the most comprehensive and cohesive account of British Leyland’s struggle so far. Cheers, Robert
Many thanks , Guys for the positive response. It’s much appreciated.
I really felt that something had to be posted to help clarify issues and to give a fair account of how events unfolded. It was a pleasure to write it up and I had the time to do it now I am retired. It was the least I could do in return for all Leyland did for me and for the great people who worked there. Leyland gave me a job and as raw student and presented the opportunities and guidance to allow me to develop a career.
I enjoyed my time with Leyland, through the ups and downs and met some really interesting and charming people over the years both in the UK and overseas. Hopefully I can meet up with some of them again through this forum.
Cheers
Some interesting stuff there Tomdhu , im particularly interested in the AEC side of things , you mention the TL12 which i think was launched around 1972 - 73 , it was rated at 272bhp which at the time was quite a powerful engine , ive read on here (not sure if its true ) that Volvo hurriedly introduced the 290 BHP 9.6 engine to combat this which had its reliability problems . In your opinion would you think if AEC had been given the funds the Marathon could have been a success , ive only heard good reports on the TL12 , the cab was improved with the Marathon 2 , wouldn`t it have been possible to “lower” the cab to fit the rest of the range much like Scania did with their range , it would have been a much better version than the ergo , was there a tendency to leave AEC products behind ,they were never fitted with the high datum ergo in fact there was very little difference on the last ergos of 1976 to the first ones produced. The last Reliances only produced 165 bhp surely they could have been tweaked to keep up with the continentals . AEC always had a great reputation before the “merger” but this seemed to nosedive soon after
The problem with the TL12 was that it wasn’t future proof in the way that the 680,let alone 14 litre ■■■■■■■■■■■■■■ which case the benchmark was never going to stay at the level of the Volvo 9.6 litre which itself used the idea of engine speed to make power in a world moving ever faster towards the idea that it’s all about torque and for torque you need an engine with sufficient stroke measurement and preferably room for more.Which at 142 mm and with a reputed main bearing centre line that was too low in the block to allow an increase for more,just wasn’t there in the case of the TL12. 
ramone:
Some interesting stuff there Tomdhu , im particularly interested in the AEC side of things , you mention the TL12 which i think was launched around 1972 - 73 , it was rated at 272bhp which at the time was quite a powerful engine , ive read on here (not sure if its true ) that Volvo hurriedly introduced the 290 BHP 9.6 engine to combat this which had its reliability problems . In your opinion would you think if AEC had been given the funds the Marathon could have been a success , ive only heard good reports on the TL12 , the cab was improved with the Marathon 2 , wouldn`t it have been possible to “lower” the cab to fit the rest of the range much like Scania did with their range , it would have been a much better version than the ergo , was there a tendency to leave AEC products behind ,they were never fitted with the high datum ergo in fact there was very little difference on the last ergos of 1976 to the first ones produced. The last Reliances only produced 165 bhp surely they could have been tweaked to keep up with the continentals . AEC always had a great reputation before the “merger” but this seemed to nosedive soon after
Hi Ramone,
There was never any strategy to leave AEC products behind. Don’t forget the Marathon was designed at AEC and I believe based on the Mandator chassis assemblies. Also it was Leyland who developed the AV505 and AV760 between 1962 and 1964.
Leyland’s strategy was to dominate only at board level. The philosophy was always to cut out the directors of the opposition. In the case of a merger, as was it BMC, they got their dominance in right at the beginning. They demanded and achieved numerical superiority on the board by assertive and, dare I say, aggressive tactics. They also held the moral high ground through leveraging their record of sales, profitability and managerial competence. Wilson and the IRC wanted an equal merger but Leyland sorted out the BMC directors in quick measure. After all they were pragmatic truckers. 
Once you sort out the main board, then the management level becomes malleable and cooperative. Leyland had a very good record of identifying the dead wood and promoting the good young talent eg George Turnbull and others at Triumph. Also Bob Fryars and others from AEC came out at the top of the combined group.
Leyland knew how best to use the staff that they acquired. Leyland would always go with the better product – wherever it came from. Just look at the Albion derived models and the GB240 series gearboxes.
As to the cab, Leyland had learned the painful lesson that a one-size-fits-all with cabs does not work. The Beaver and Mandator etc, etc were adversely affected (with cooling problems) by the low slung Ergo cab.
In my view the best value cab they had was the one they inherited from Bathgate. It served light & medium weight models (particularly the Albions) very well for many years. It did very well in export markets. OK it wasn’t hi-tech but it was cheap to produce, durable and very adaptable.
With the technology in the early 70’s it maybe no surprise that the Volvo 9.6L was a bit problematic but I couldn’t comment on it as I have no direct experience with it.
As for the Reliances, I would guess this would be part of the on-going rationalisation process. After any merger you cannot keep two competing models in-house and of course there was the costs off metrication to consider. The better one must get preference for scarce development funds and I guess the Leyland Tiger and Worldmaster won out.
ramone:
Some interesting stuff there Tomdhu , im particularly interested in the AEC side of things , you mention the TL12 which i think was launched around 1972 - 73 , it was rated at 272bhp which at the time was quite a powerful engine , ive read on here (not sure if its true ) that Volvo hurriedly introduced the 290 BHP 9.6 engine to combat this which had its reliability problems . In your opinion would you think if AEC had been given the funds the Marathon could have been a success , ive only heard good reports on the TL12 , the cab was improved with the Marathon 2 , wouldn`t it have been possible to “lower” the cab to fit the rest of the range much like Scania did with their range , it would have been a much better version than the ergo , was there a tendency to leave AEC products behind ,they were never fitted with the high datum ergo in fact there was very little difference on the last ergos of 1976 to the first ones produced. The last Reliances only produced 165 bhp surely they could have been tweaked to keep up with the continentals . AEC always had a great reputation before the “merger” but this seemed to nosedive soon after
I had always thought that this reduction in output from the 760 was because the Reliance had a (normal) spiral bevel diff, which probably couldn’t tolerate the torque of a fully rated engine. The other applications of this fully rated engine were always mated with the heavy duty double reduction diff AFAIK.
I would like to add my appreciation and thanks for the insights from Tomdhu. The only comment I can think of is that as far as dimensions are concerned AEC engines were metric nominally, the threads however were imperial.
Carryfast:
The problem with the TL12 was that it wasn’t future proof in the way that the 680,let alone 14 litre ■■■■■■■■■■■■■■ which case the benchmark was never going to stay at the level of the Volvo 9.6 litre which itself used the idea of engine speed to make power in a world moving ever faster towards the idea that it’s all about torque and for torque you need an engine with sufficient stroke measurement and preferably room for more.Which at 142 mm and with a reputed main bearing centre line that was too low in the block to allow an increase for more,just wasn’t there in the case of the TL12.
Hi CF,
There’s been a lot of exchanges about the respective development potential of the AV760 and the O.680 and you have highlighted the main reason as the fact that the C/L of the AEC crank is at the sump edge level and the Leyland is buried in the block.
Don’t you think two more relevant parameters are…
(1) The distance from the C/L of the crankshaft to the top of the cylinder block? ,and
(2) The distance from the C/L of the crankshaft to the bottom of the cylinder bores?
Tomdhu:
There was never any strategy to leave AEC products behind. Don’t forget the Marathon was designed at AEC and I believe based on the Mandator chassis assemblies. Also it was Leyland who developed the AV505 and AV760 between 1962 and 1964.
Ironically it was probably more a case that the Group actually needed a successful AEC not a case of trying to get rid of it which so many seem to think.While the eventual move by Scammell and Guy and then Leyland as a whole to outside engine suppliers shows that use of the best product philosophy in action.
Which raises the question if the 760 was a Leyland instigated product why would they have limited themselves to the previous AEC design regards the previous AEC generation 590 and 690 stroke measurement and,what seems to have been ?,a bored out version of same thereby leaving themselves in the worst of all worlds situation of a larger overall capacity than the 680 but with a shorter stroke.With an engine architecture that wouldn’t allow any increase in that. 
I had always thought that this reduction in output from the 760 was because the Reliance had a (normal) spiral bevel diff, which probably couldn’t tolerate the torque of a fully rated engine. The other applications of this fully rated engine were always mated with the heavy duty double reduction diff AFAIK.
This alone would have been a very good reason for not allocating scarce development funds to the Reliance in comparison with the Leyland model.
I would like to add my appreciation and thanks for the insights from Tomdhu.
Many thanks, much appreciated
The only comment I can think of is that as far as dimensions are concerned AEC engines were metric nominally, the threads however were imperial.
[/quote]
Very true, but the European markets demanded metric threads so they could use metric spanners in maintenance. We were brought up on Imperial but can you imagine someone who was trained on Metric getting their heads round 3/8" AF, 3/8" Whitworth and 1/2" pipe spanners.
The AEC V8 and the Leyland O.500 were the first metric engines from the group and were intended to spearhead the push into Europe.
I wonder whether AEC scuppered themselves back in 1954 when the AV 590 was introduced . AEC was in the position of being the obligated contractual supplier of chassis to London Transport, with whom at the time they were jointly designing the Routemaster bus. Historically this had been their core business everything else being a bonus. Their previous engine model range were all separate crankcase designs whereas their new baby was a monobloc. Without giving it a great deal of thought, I wonder if sump clearance issues above the independent suspension crossmember dictated the overall height of the block.
Leyland however had no such possible constraints and had been free to produce the O600 engine in 1946 with the potential to increase both stroke and bore. When many years later the DAF DK1160 engine was fitted experimentally to one of these vehicles it was mounted slightly higher in the chassis and had to have a special sump and coolant header tank.
Tomdhu:
Carryfast:
The problem with the TL12 was that it wasn’t future proof in the way that the 680,let alone 14 litre ■■■■■■■■■■■■■■ which case the benchmark was never going to stay at the level of the Volvo 9.6 litre which itself used the idea of engine speed to make power in a world moving ever faster towards the idea that it’s all about torque and for torque you need an engine with sufficient stroke measurement and preferably room for more.Which at 142 mm and with a reputed main bearing centre line that was too low in the block to allow an increase for more,just wasn’t there in the case of the TL12.Hi CF,
There’s been a lot of exchanges about the respective development potential of the AV760 and the O.680 and you have highlighted the main reason as the fact that the C/L of the AEC crank is at the sump edge level and the Leyland is buried in the block.
Don’t you think two more relevant parameters are…
(1) The distance from the C/L of the crankshaft to the top of the cylinder block? ,and
(2) The distance from the C/L of the crankshaft to the bottom of the cylinder bores?
Having not had the chance to see both engines in stripped form,or detailed knowledge of the architecture,I’d only recently heard that as being the,if not an,issue with the 760 in a post by cav551 on a different topic ( DAF Engines ).
Obviously stroking an engine is going to require all the relevant clearances at both TDC and BDC in addition to enough side clearances to accept the larger side throws of crank.Only having cav’s comments to go by I was just guessing that it was the clearance at BDC which was the problem in the case of the 760 ?.
While the topic in question also resulted in my question did the 680’s basic engine architecture also actually have the required potential in all those parameters to provide the further increase to 158 mm in the case of the XF and possibly beyond in the case of the MX 13 in the hands of DAF. 
gingerfold:
Stanley Markland would have been a much better choice to head up the organisation than Donald Stokes.
Ironically it seems to have been an argument about the post previously held by Spurrier,which went to AEC’s Black,which caused Markland’s decision to resign.With history repeating itself in that regard in the case of Turnbull v Barber.While regardless of who was at the top of the tree,the questions,as to how the potential of the 680 v the downsides of the 760 wasn’t recognised and how DAF got its hands on the development of the former,while Leyland was left holding the latter,remain.
As does the question as to how did the 760’s architecture seem to have been limited by being based on the previous 590/690 design,instead of its designers being given a clean sheet.On that note compare the solution made by Triumph’s engineers in the case of the need to upgrade the 2000 car engine,to that of the 760 truck engine’s designers,bearing in mind that torque was/should have been the aim in both cases. Those questions can only logically rest with the relevant engineering department heads and not top management.
There was never any strategy to leave AEC products behind. Don’t forget the Marathon was designed at AEC and I believe based on the Mandator chassis assemblies. Also it was Leyland who developed the AV505 and AV760 between 1962 and 1964.
Leyland’s strategy was to dominate only at board level. The philosophy was always to cut out the directors of the opposition. In the case of a merger, as was it BMC, they got their dominance in right at the beginning. They demanded and achieved numerical superiority on the board by assertive and, dare I say, aggressive tactics. They also held the moral high ground through leveraging their record of sales, profitability and managerial competence. Wilson and the IRC wanted an equal merger but Leyland sorted out the BMC directors in quick measure. After all they were pragmatic truckers.
Once you sort out the main board, then the management level becomes malleable and cooperative. Leyland had a very good record of identifying the dead wood and promoting the good young talent eg George Turnbull and others at Triumph. Also Bob Fryars and others from AEC came out at the top of the combined group.
Leyland knew how best to use the staff that they acquired. Leyland would always go with the better product – wherever it came from. Just look at the Albion derived models and the GB240 series gearboxes.
As to the cab, Leyland had learned the painful lesson that a one-size-fits-all with cabs does not work. The Beaver and Mandator etc, etc were adversely affected (with cooling problems) by the low slung Ergo cab.
In my view the best value cab they had was the one they inherited from Bathgate. It served light & medium weight models (particularly the Albions) very well for many years. It did very well in export markets. OK it wasn’t hi-tech but it was cheap to produce, durable and very adaptable.
As for the Reliances, I would guess this would be part of the on-going rationalisation process. After any merger you cannot keep two competing models in-house and of course there was the costs off metrication to consider. The better one must get preference for scarce development funds and I guess the Leyland Tiger and Worldmaster won out.
[/quote]
Morning all
Fascinating stuff! Such a contrast to the world that I worked in with the Saviem Berliet merger where the product ranges were duplicated in all market sectors, the management kept separate, as were the (competing) Dealer networks. Not only in France, but in her export markets as well. This led, (no surprise), to loss in market share for both marques, both in the domestic market, and export.
How bad could it get…well, cringeworthy comes to mind…Suisse Show 1980, combined stand for Saviem and Berliet, and the first use of the Renault" Brand"…Same year, Amsterdam, same big cheese giving the address…three stands, Saviem, (celebrating our Importer investing in a new facility)…Berliet…more investment…and Renault lightweights all away with yet another importer.
Then there were the actual lorries…Berliet were masters at duplicating their models, (Stradair/G range)…then it was decided, (despite several of us voicing total opposition), that the Saviem Serie J should become the Berliet Serie B for the Berliet dealerships…(and duplicating three existing models. These decisions were taken outside of the actual “works” by “politicians”, more mindfull of employment and regional issues, not the overall progress of the combined company.
The internal politics were horrendous…and it was a truly exciting place to be in the 70s!!!
But you should have seen the faces of the “big cheeses” when I gave a presentation with the fact that Leyland had sold more Marathon/T45s in France (at that date), than combined Berliet Saviem sales in the UK! …
Fascinating stuff Tomdhu, please keep on
Cheerio for now.
Carryfast:
Tomdhu:
There was never any strategy to leave AEC products behind. Don’t forget the Marathon was designed at AEC and I believe based on the Mandator chassis assemblies. Also it was Leyland who developed the AV505 and AV760 between 1962 and 1964.Ironically it was probably more a case that the Group actually needed a successful AEC not a case of trying to get rid of it which so many seem to think.While the eventual move by Scammell and Guy and then Leyland as a whole to outside engine suppliers shows that use of the best product philosophy in action.
Which raises the question if the 760 was a Leyland instigated product why would they have limited themselves to the previous AEC design regards the previous AEC generation 590 and 690 stroke measurement and,what seems to have been ?,a bored out version of same thereby leaving themselves in the worst of all worlds situation of a larger overall capacity than the 680 but with a shorter stroke.With an engine architecture that wouldn’t allow any increase in that.
Yes the Group needed AEC primarily as the market demand was such that all the plants were working flat out to meet it. AEC, Guy and Scammell plants were very cramped and along with Leyland, most of their machine tools were pretty clapped out after the war. The plants needed to be kept in production until the the new tooling for the V8 started production. Shortly after which the big new facility for the O.500 would come on stream. So it was a matter of keeping the existing kit going for the time being.
Saviem:
There was never any strategy to leave AEC products behind. Don’t forget the Marathon was designed at AEC and I believe based on the Mandator chassis assemblies. Also it was Leyland who developed the AV505 and AV760 between 1962 and 1964.Leyland’s strategy was to dominate only at board level. The philosophy was always to cut out the directors of the opposition. In the case of a merger, as was it BMC, they got their dominance in right at the beginning. They demanded and achieved numerical superiority on the board by assertive and, dare I say, aggressive tactics. They also held the moral high ground through leveraging their record of sales, profitability and managerial competence. Wilson and the IRC wanted an equal merger but Leyland sorted out the BMC directors in quick measure. After all they were pragmatic truckers.
Once you sort out the main board, then the management level becomes malleable and cooperative. Leyland had a very good record of identifying the dead wood and promoting the good young talent eg George Turnbull and others at Triumph. Also Bob Fryars and others from AEC came out at the top of the combined group.
Leyland knew how best to use the staff that they acquired. Leyland would always go with the better product – wherever it came from. Just look at the Albion derived models and the GB240 series gearboxes.
As to the cab, Leyland had learned the painful lesson that a one-size-fits-all with cabs does not work. The Beaver and Mandator etc, etc were adversely affected (with cooling problems) by the low slung Ergo cab.
In my view the best value cab they had was the one they inherited from Bathgate. It served light & medium weight models (particularly the Albions) very well for many years. It did very well in export markets. OK it wasn’t hi-tech but it was cheap to produce, durable and very adaptable.
As for the Reliances, I would guess this would be part of the on-going rationalisation process. After any merger you cannot keep two competing models in-house and of course there was the costs off metrication to consider. The better one must get preference for scarce development funds and I guess the Leyland Tiger and Worldmaster won out.
Morning all
Fascinating stuff! Such a contrast to the world that I worked in with the Saviem Berliet merger where the product ranges were duplicated in all market sectors, the management kept separate, as were the (competing) Dealer networks. Not only in France, but in her export markets as well. This led, (no surprise), to loss in market share for both marques, both in the domestic market, and export.
How bad could it get…well, cringeworthy comes to mind…Suisse Show 1980, combined stand for Saviem and Berliet, and the first use of the Renault" Brand"…Same year, Amsterdam, same big cheese giving the address…three stands, Saviem, (celebrating our Importer investing in a new facility)…Berliet…more investment…and Renault lightweights all away with yet another importer.
Then there were the actual lorries…Berliet were masters at duplicating their models, (Stradair/G range)…then it was decided, (despite several of us voicing total opposition), that the Saviem Serie J should become the Berliet Serie B for the Berliet dealerships…(and duplicating three existing models. These decisions were taken outside of the actual “works” by “politicians”, more mindfull of employment and regional issues, not the overall progress of the combined company.
The internal politics were horrendous…and it was a truly exciting place to be in the 70s!!!
But you should have seen the faces of the “big cheeses” when I gave a presentation with the fact that Leyland had sold more Marathon/T45s in France (at that date), than combined Berliet Saviem sales in the UK! …
Fascinating stuff Tomdhu, please keep on
Cheerio for now.
[/quote]
Hi Saviem,
You have expanded nicely on the crucial issue of post merger dynamics both in terms of management and marketing.
Leyland solved the management one by taking no prisoners at the main board level. At the market level, they recognised the problem of brand loyalty on the part of the operators and did not making sweeping rationalisation moves early on – with the exception of the Ergo cab on AEC, Leyland and some Albion models.
Trucking had expanded hugely in the fifties and early sixties with the decline of the railways, motorways and the general expansion of the economy in the post war era. The small operators were expanding and many would have started out as owner drivers. If they had a good experience with that first truck, they would attribute their success to that truck and its actual brand.
The operator would know that truck intimately – just like an integral member of the family, so to speak. He would have invested in the tools and some spares like injectors, fan belts and manuals etc. He would have struck up a relaxed personal relationship with the salesman at the dealership so he was wedded to that make.
The resistance to changing marque then was well entrenched hence Saviem’s and Leyland’s separate product streams.
The first big step in the rationalisation which the truckers would have to swallow was when the engines were rationalised and became identical across the board. Best to do this with a completely new engine hence Leyland’s new O.500 and the V8.
I would very much like to hear from you as to how the French tackled the engine side of things.
Carryfast:
gingerfold:
Stanley Markland would have been a much better choice to head up the organisation than Donald Stokes.Ironically it seems to have been an argument about the post previously held by Spurrier,which went to AEC’s Black,which caused Markland’s decision to resign.With history repeating itself in that regard in the case of Turnbull v Barber.While regardless of who was at the top of the tree,the questions,as to how the potential of the 680 v the downsides of the 760 wasn’t recognised and how DAF got its hands on the development of the former,while Leyland was left holding the latter,remain.
As does the question as to how did the 760’s architecture seem to have been limited by being based on the previous 590/690 design,instead of its designers being given a clean sheet.:
The reality is that “clean sheets” take time, cost really big money and come with potential risk.
The time is consumed in design, development and proving.
The big money comes in the cost developing patterns and/for casting moulds but mostly in machine tools.
The potential risk is always there as it might be a dud.
AEC themselves had started with a clean sheet by initiating the V8 engine range and look what happened to that.
Leyland started with a clean sheet with the O.500 and look what happened to that.
Tomdhu:
gingerfold:
Tomdhu, thank you for your concise and knowledgeable insights into a complex subject that has fascinated many people for years. I have to say that your opinions echo very closely those of Robert Fryars, whose opinions I have heard for many years. As you will know, Robert Fryars rose to very senior positions in AEC and then Leyland Motors. Whilst Mr Fryars is more scathing in his opinions of certain people and personalities within British Leyland than you are, like you he is of the opinion that Stanley Markland would have been a much better choice to head up the organisation than Donald Stokes. It is good for me personally that I am now able to read about BL from both an AEC and a Leyland man’s viewpoint and it is pleasing that there is so much common ground within the two opinions.Hi GF,
Do you know if “Kinda Bob” as we knew him is still alive and if R k Knowles is still around?
Hi Tomdhu, yes Bob Fryars is still going strong and he has written many articles about his experiences at both AEC and Leyland for the AEC Gazette and AEC Bulletin. All of his reminiscences are fascinating and some of the technical articles about product design and development are brilliant and even a non-engineer like me can understand what he is writing about. I don’t know R.K Knowles, but I do know Mike Knowles.
Taking a step back to the 1950s and looking at AEC as a company, and I am using Bob Fryars’ writings as my source. In the 1950s AEC was a moribund organisation with a dated product catalogue. When A.J. Romer retired there was no chief executive appointed and the company was run by committee, (never a recipe for success in my own experience). Romer was regarded as a weak and indecisive executive and the successful medium weight Mercury and Reliance ranges, into which Bob Fryars had an input as a young engineer, came about despite Romer rather than because of him. AEC as a company was rudderless in its management but the engineers and sales team did manage to instigate the Mk.V range development programme. By the late 1950s AEC was seeking an amalgamation and lengthy negotiations started with BMC. A deal was almost concluded but at the last minute AEC pulled out, no doubt they were terrified when they looked at BMC in detail. Following this they acquired Thornycroft and then actively sought a merger with Leyland. It has always been believed that Leyland was the predator for AEC, but in fact AEC approached Leyland, who at first weren’t too interested! By the early '60s AEC was getting itself back on track and Europe had been identified as a potential lucrative export market. Jim Slater, who died a few weeks ago, was the driving force behind the European expansion for AEC, and he had come from Park Royal Vehicles, which AEC had acquired of course. Jim Slater resigned from the malgamated AEC / Leyland group to join forces with Peter Walker and they both had a successful period for a few with a venture capital finance business. For a time in the early years of the merger both companies kept separate boards of directors with Donald Stokes and Stanley Markland sitting on the AEC Board. For the 12 months or so before he resigned, Stanley Markland shook AEC out of its lethargy and he was a force for good at Southall.
Hi Tomdhu- I will echo the sentiments of the others, in thanking you for taking the time to answer our questions. The knowledge of a senior employee of such a fascinating company as Leyland is gold dust to nutcases like us.
I note that you received some tuition from Donald Stokes. Elsewhere on this forum, I cited his obituary in the Telegraph:
telegraph.co.uk/news/obituar … tokes.html
“…Stokes returned to Leyland Motors with a visionary’s zeal for the sort of markets where the company should be selling its products. He argued that European countries would be developing their own truck and bus plants and that Leyland should go for the Middle East and South America. He was given the job of running the new export department in 1946 and began putting his philosophy into effect…”
Is the above quote fair? Did he really chicken out of the European markets?
When the 0600 engine was being designed I think the engineers at Leyland Motors must have had better eye on future potential development than their equivalent engineers at The AEC. The O680 engine was introduced only a matter of about a couple of years after the 0600. Leyland Motors were able to both stroke and bore their engine while still maintaining the same external envelope. This was something that clearly the design of The AEC’s engine precluded if the crankshaft swing clearance at BDC was insufficient. Any attempt to stroke the engine would have required a taller and maybe fatter block, with the crankshaft centre line already at sump face level, it was game over.
As a postscript: I have just recalled conversations many years ago with those who lived in Southall and who had family working for the company. The company was always referred to as THE AEC.