The Oxford English Dictionary also (indirectly) credits Hylda Baker with the earliest use of the phrase; it cites the script of the Granada TV programme Nearest and Dearest; Series 2, Episode 1, [July 8 1969].
Eli [Jimmy Jewel] 'Go round talking like that, you'll be hearing from our solicitor.'
Nellie [Hylda Baker] 'He is our solicitor, you big girl's blouse.'

Matthew