My suggestions from this thread (
http://leadadventureforum.com/index.php?topic=20738.0 ) about Quatermass a couple of years ago probably still hold, but I hope there's others to add by now;
"Possible 28mm mini ranges for 1950s Britain: pick and choose from Black Tree Doctor Who, any WW2, 1st Corps Korean War, Musketeer Inter-War/VBCW, Brigade Games Atomic Cafe, Killer B Geezers. Possibly add green stuff quiffs and crepe soles onto Victorian Gents to create Teddy Boys."
(
Edit: You could now add Crooked Dice and Mutton Chop to that list, used selectively.)
See alo this post about background and inspiration for 1950s Britain in AC57:
http://leadadventureforum.com/index.php?topic=16260.msg258351#msg258351