E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Priest of the Blue-bag.
A barrister. A blue-bag is a cant name for a barrister. (See BARRISTERS BAG.)
He [OFlynn] had twice pleaded his own cause, without help of attorney, and showed himself as practised in every law quibble as if he had been a regularly ordained priest of the blue bag.C. Kingsley: Alton Locke, chap. xx.