Signed in pen means it was a legit sale, unsigned means it may have slipped out during the production process. He wrote about it in "The Art of Brian Bolland" book. He reckons there were about 110 pages never returned to him and he considers them stolen.
He doesn't mince his words. "All the pages that were returned to me and sold were signed by me. If you own one without my signature it was stolen and I want it back."
