That’s what’s supposed to happen Big-Jon. I’ve seen many a modern trailer move.
Spring brakes sometimes fail. I don’t know why.
Hence why in driver’s hand books & H&S rules, trl brake must be checked as on before reversing under.
Live and learn mate…never say never. A timely lesson learned with no injuries and no damage, I’d say thats a result an dgive thanks for it 
shade:
been there done that … lesson learnt , won’t be doing that in a hurry again I can tell ya
Same here mate!!
I didn’t realise I was rolling, so let’s just say there was an ‘impact.’ 
and I got a DCM for my troubles.
One of my drivers nearly went under the wheels of his unit after panicking, jumping off the back and trying to get in the cab to put the hand brake on.
The main thing that gets most blokes that this happens to is that you may not even feel that you are moving until you are some way toward disaster as you have no point of back ground scenery reference if you are just looking at the suzies. Always worth having a bit of a look around whilst you’re putting the suzies on. I usually double check the hand brake then once i’ve got out of the cab have another quick look back in the cab once my feet hit the ground.