The Thirty-Nine Steps Why 1945 to 1966?

I had to decide on a 'cut off' point and made the decision that I would collect up to the time that PAN changed from their own numbering system to the use of ISBN
(International Standard Book Numbers)

"The Thirty-Nine Steps" showing the change of logo style

The Thirty-Nine Steps
PAN G218 from 1961 PAN G218 from 1967


Some volumes ssued between 1963 and 1967 had numbering systems consisting of  T1 to T51 , E1 to E5 and  H1 to H3

The PAN Piper series ran from 1963 to 1967 and were numbered MP1 to HP127

The Science Fiction series started in 1970