Probably because of the time (50’s & 60’s) World Distributers (don’t know where the “L” comes from) seem to have done a lot of second world war related titles both fiction and non-fiction. John Steinbeck’s East of Eden is notable because of the James Dean cover, Frankenstein and Swingin Dors are also not that easy to get hold of.
I can’t put a payment button up as the prices vary, so you will have to contact me if any of the titles interest you. I have, up to date catalogued 6,648 paperbacks, and though I am slowly working through a stock check, I am 95% confident that I know where most of the books listed are.
I also have a very large number of SF digests, not counting the 50 foot of paperbacks, but I have not got round to cataloguing them yet.