Uk Box Office Records?

I have nearly every U.S. top ten horror movie released since 1922, but information relevant to the British box office seems to be much more scarce.

What was the tradepaper they used to record what was hot each week in the cinemas? Box Office Mojo only has limited data beginning from 1996, or 2000.

I find that peculiar, because the UK has to be just as big as North America, surely.