I believe I've never purchased any item from Ken Bulmer, but I still own quite a few, since he is so very often the other half on Ace Doubles that I have (or had). He was a very prolific author, using other aliases in some cases.

I loved "Fugitive of the Stars" (by Hamilton), and am not sure where I first read it (not as a double). It's good honest space opera, and fun. I recommend it (although you need to take off your 21st century hat, and put on the one from 1965, to really enjoy it). ( )