The coach in which he travels looks like a Mark 2A (or maybe 2B or 2C) Corridor First or Brake First, and the restaurant car is obviously a Mark 1 (probably a Restaurant Buffet). I would guess that it was filmed only a few months before the first Mark 2D air-conditioned coaches entered service on the East Coast Main Line.
You can see the train journey scene at
I would guess that in those days it would have taken about 4 hours. What happens in films doesn't necessarily reflect what would happen in that kind of situation in real life, though.