Mid-80's bomb shelter short - UNSOLVED

I've also posted this on INTK and other forums, but I figured there's just as good a chance someone here will know it.

It was British, and set in contemporary times, but I don't recall anyone well-known in it. The plot revolved around a young man who is paranoid about a nuclear war breaking out, and builds himself a fall-out shelter in his rented house, stocking it with all the tinned food he can get his hands on. He must have fallen behind on his rent, as his landlord keeps coming round and arguing with him. He is at the supermarket buying more food - several trays of baked beans if I remember rightly - when the four minute warning sounds. The young man races frantically back home only to find that his landlord has come round and found his shelter, sealing himself in and our hero out. There was very little, or no, dialogue... except for TV and radio news bulletins about the build-up to war.
The final shot is of our hero sat despondently on the front step awaiting his doom... and then realising that he has in his hand the only tin opener in the house.

I think I saw this in around 1983-85, probably attached to Return Of The Jedi, Clockwise or The Last Starfighter. Come to think of it, it might have been in front of one of the Star Trek movies. If anyone knows the title, and if it's online anywhere, I'd love to see it again!

----------------------------------------

"I'm just as God made me, Sir".