A Bibliography of Stephen Leacock by Carl Spadoni (Toronto: ECW Press, 1998), pages 97 and 98, notes that the Penguin edition sold over 46,000 copies in the first five months after publication. The bibliography also notes that McClelland & Stewart held the Canadian rights to the book and refused Collins (who were Penguin's agent in Canada) permission to sell the Penguin edition in Canada. But in 1945, the year after Leacock died, Collins was able to publish the first Canadian paperback edition. The Collins edition has been printed from the same plates as the Penguin edition.
The Penguin edition has a short biography of Leacock but no introduction. B. K. Sandwell, a Canadian editor and author, provided a three page introduction to the Collins edition which also had a couple of photographs of Leacock by the celebrity photographer of the day, Karsh. The NCL edition has a five page introduction by Robertson Davies and remains in print. The texts are the same except the NCL edition doesn't have a one page of acknowledgements from the author.
Penguin 212 back cover
Penguin 212 DJ flaps
White Circle 213 - Margaret Paull artist
White Circle 213 back cover
New Canadian Library 3
New Canadian Library 3 back cover