Ill make this as simple as possible. A friends brother had a breakdown the other morning and rang him to ask his opinion.Had a breakdown with the taillift,major problem with the ram. Informed his office of the problem,as hed been on duty since midnight,and was starting to get panicky,as time was moving on and he would be nearing his spreadover time ,if he didnt get back to base (with three 1/2 hour drive). He wanted a b&b if his 15hrs was approaching(no sleeper cab/gear) They told him,no bother drive on,and record "unforeseen circumstances". He didnt think that was right and an argument ensued.In the heel of the hunt anyway,he did make it back to base with 10 mins to spare.
Another argument.Rattles thrown out of prams etc.,
He rang the RSA,(our version of VOSA)without the jackboots,and he was told by a department official,that it is quite okay to break the 15 hr rule 
,(obviously so long as the driving hours and breaks are observed),in order to make it home,so long as its not too much!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! This is not a scenario where you have two hours, to do three miles and theres a motorway pileup,and is unavoidable.
Are we correct in saying 15 hours are 15 hours?No exclusions
You can go over 15 hrs in unforeseen circumstances to find a safe and secure place to park so you can argue that getting back to base is a safer place than a layby but it depends how far over you go, if you pass umpteen laybys and MSA’S to get to base after 17 hrs that i’m sure is a no no.