a banned film

In the late 1950s/early 1960 a British film was released that supposedly showed the effects of a nuclear attack on a British city so realistically and horrifically that it was only released in the 1980s.
I can only remember seeing a minute long clip and so all I can remember was that it was in black and white.
Any idea what it was called/where I can lay my hands on it, it was slightly intriguing from what I can remember, which isn’t much.

I believe you’re talking about Peter Watkins’s “The War Game”, a pseudo-documentary about the after-effects of a nuclear strike on London. It was never banned that I know of, but it is an absolutely horrifying movie and wrenching to sit through. Highly recommended! For more info, go to http://www.imdb.com.

I’m fairly sure it was never banned, but gained such a reputation for being disturbing that it was never repeated.

You can right to the IMDB page at this link