Polmont
Polmont rail crash, 30 July 1984; 13 killed, 44 injured: leading DBSO of Edinburgh to Glasgow train hit stray cow on line, total train derailed
Although I think this was affected badly by the fact that the rule to have the locomotive at the front of trains travelling over a certain speed had been relaxed previously, so the front of the train was derailed but the weight of the train was concentrated at the back.