1). I believe it was in 1963/64. The customary procedure then was to lock the doors of sleeper trains to prevent somnambulists hurting themselves.
Dirty linen was piled up against a heater and 16 people died. Nothing to do with seats directly. However, they have to take in to account the youth of today who will slash a seat, pour in lighter fuel and set it alight. Yes, really and they are traveling on the train!!!
2). If you want to see how the foam does NOT catch fire go to
www.ifoamltd.com and click on the testing & certification tab. Scroll down to the video titled “what happens when Graphite Foam encounters a naked flame”. Now you can sleep well in the knowledge of how safe you are on a (modern) UK train. Yes there is usually a fire blocker between the foam and the covering material - but not always - it’s what passes the tests.
3). Yes, see the last part of answer 1
4). Sometimes. There are three categories of fire retardance. It’s a little complicated but basically if the train doesn’t go through any long trains and it can just stop and be evacuated it’s Cat2.
If there are ‘long’ tunnels, viaducts, bridges etc. it’s Cat1b (most TOC’s ask for this now) and finally if it spends it’s life underground it’s Cat1a.