Thanks guys,
I was down a country lane (50 limit) doing probably no more than 50, but I did brake late for the bend. The rears locked up and it fishtailed from right to left and I hit the side of the other car doing about 15 mph I suppose. A person with slightly more skill would have avoided the accident altogether. The other car just had some slight damage to the door/wing area.
The rears locking are making me think I may have a problem with the fronts brakes! (I'll check the road tomorrow for diesel etc) The Police turned, up but as there was no-one hurt they were happy to leave us to it.
From my initial inspection, the main structure of the chassis is untouched. All the suspension, steering, wheels etc all seem to be straight and undamaged (it steered straight while being towed home) It may just be the box section forward of the suspension that is out of line.
I do try to drive sensibly on the roads, I'm sure it would be very easy to let one of these cars get WAY out of control if you're really stupid, and I'm VERY aware of my own limitations.
Simon