Robbo,
When my dad was a student (in the early 1950's), he bought the complete volumes of all Signals ever produced. Those are four years bound in leather (about 4 fingers thick each), the rest are loose numbers. You still find loose numbers at flea markets in Belgium occasionally. However, I can't remember ever having seen any pinups in there

. I'll check that tonight. Next thing you'll tell me that I have to file them with my hidden collection of Playboy to avoid incidents with our (muslim) cleaning lady ! :-)
The latest editions have more color pictures than those of 1939 through 1943, though.