I was one of the "lucky" many who escaped the crash without a scratch. A few of my experiences/thoughts.
I got on coach C (I think) at Reading: I remember passing Ealing Broadway and Acton on the HST, reading my newspaper when I was aware of screaming, then the the train started juddering and slowing. I was not aware of any emergency braking. Looking back I seem to be aware of a "woomph" type noise and the feeling that the train was going though something insubstantial. I thought the train had derailed.
The train seemed to continue for an age until slowly passing past burning debris. This was almost surreal. We passed a long piece of metal which was at an angle to the vertical. I thought it was an electrification mast that we had hit. Turned out to be part of the Thames Turbo.
After the train stopped it seemed to take an age to be able to get off. Several passengers were emotionally distressed. There was burning debris outside and I was worried that the fire would spread to the coach or that smoke would start coming in. Once out of and clear of the train I looked at my watch. It was 08:20. The BBC said that the crash happened at 08:11 so I reckon it took seven or eight minutes to get out.
Once I reached the door I asked whethert the door in the adjacent coach was open. It wasn't and at that momemnt someone kicked it. I suggested that they check with railway? people outside the train (in case the door hit someone) and there was a shout from outside to break the glass panel above the door. The man did this (by hand) and released the door. Everybody had obviously assumed that the doors had been unlocked and were jammed by the crash.
After getting down from the coach, we made our way over the adjacent tracks (and power cables) to the North Star Depot security fence. It was at this point that I saw two badly burned people and wondered where they had come from. Then I realised that we were amongst the shattered remains of a Thames Turbo coach. The remains reminded me of pieces of fuselage after a plane crash. We could only see about one coach length in the Paddington direction because of the plume of smoke rising. This did not stop someone (railway staff?) directing us in this direction (even after I suggested that this might not be the best cause of action). We soon stopped and were eventually evacuated in the opposite direction.
I was shocked (and still am) at the damage (understatement) to the Thames Turbo, these are the trains I normally travel on (missed my usual train due to having to de-ice the car). Didn't see the damage to the HST due to the smoke. This looked very bad on the television.
The police and fire brigade seemed to turn up fairly quickly but we didn't see many ambulance men.
We made our way up the embankment to the Sainsbury's store. We were offered tea and sympathy by the staff (and first aid for those who needed it), some of whome were traumatised themselves. One had been in the petrol sation when a fireball erupted (her words) and someone had told her to get away from the petrol Another told me she had seen things she had never wanted to see.
Police (and one passenger who "had no adreneline") took our names and addresses. No other statements.