Who?
Herbert Leonard Stevens, Or mostly referred to as Len. He was in a lot of early library labels, like FDH, Chappell, Conroy & even EMI Photoplay i think.
How do you know Len was in EMI Photoplay? The only thing I know about this library is that the majority of these cues (most specifically, those composed by Phillip Green) were used in various American media throughout 50's and 60's. The most notable examples I can think of are the first Ronald McDonald commercial, cartoons by Hanna-Barbera and even a taping of a Bozo the Clown show episode from the 1960s. I think my only guess about Len's time at Photoplay was that he composed a variety of tracks in the 1970s.
There is a track from EMI Photoplay's sucessor label Photoplay Q that was re-issued through a Carlin album that credits Len Stevens and Frank Barber, but in actuality, that track was originally only composed by Barber himself, without Len Stevens (I think it's original name was "Santiago Splashdown"). There are also two other Photoplay Q tracks from Frank Barber that were re-issued on other Carlin albums, but their re-issues miscredit Barber as Len Stevens and, unlike Santiago Splashdown's re-issue, doesn't credit Frank Barber as well. There were a series of 12 Conroy tracks from BMLP 085 named the "Editunes" tracks that were composed by Barber and Stevens together.