By all accounts it was one of Hylda Baker's catchphrases:

'Born on 4th February 1908 in Farnworth...Hylda Baker was very tiny at 4ft11inches but had tremendous energy and she worked her way up the entertainment ladder via the Music Halls, where she played a fast-talking gossip, aided by her gormless on-stage 'stooge' Cynthia (always played by a man). She developed a string of catch-phrases such as 'She knows, you know', "You big girl's blouse' and 'Be soon', and she became a master of the malapropism and double entendre – such as "I can say that without fear of contraception" and "You haven't had the pleasure of me yet".'
http://www.prideofmanchester.com/comedy/hyldabaker.htm