Thanks for all the hugs and stuff, we're both very touched - you almost have me in tears - let alone Pearl!
   For the technically curious, yes we did have an Alco hitch and a stabiliser. A 'caravan' or ''van' is a 'trailor' across the 'oggin, and a 'snake' (fishtail?)is the condition when a tow for whatever reason, becomes unstable and starts to swing from side to side with increasing momentum until it starts to take tow vehicle with it. After that there's no hope or possibility of pulling out of it and where you end up is in the lap of the gods. In our case, straddling two lanes of the motorway with the 'van on it's side. All this, of course, happened in seconds.
   We think what caused the 'van to be thrown out of kilter (and this seemed to be the opinion of everyone we spoke to on site) was a burst tyre at 55/60 mph. Which is bloody annoying because the tyre that burst was a new one! The evidence was there in the badly damaged rim which had obviously been run on and the fact that Pearl smelt burning rubber just before the incident.
   Anyway, I hope that answers the questions. 36 hours later we're both still a little stiff and sore but I think we're both over the shock and a little bit more accepting of what has happened.
Once again, thanks for all your kind thoughts...
Love and Regards;
Tony and Pearl