'A hero of an older man got in the way as the attacker tried to stab a young girl'

Mr Day said he told them “no, you’ve got to let us in”.

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He then saw “a man at the window with his knife” trying to get in, but by then the buffet car was already locked.

He recalled a passenger in a Nottingham Forest tracksuit saying: “I’m gonna go confront him.”

Mr Day added: “He wasn’t the biggest guy and we tried to stop him.”

He later saw the same man “on the platform afterwards, flat-out, covered in blood”, having been stabbed in the chest.