E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
In the Common Law bar, barristers bags are either red or dark blue. Red bags are reserved for Queens Counsel and sergeants; but a stuff gownsman may carry one if presented with it by a silk. Only red bags may be taken into Common Law Courts: blue bags must be carried no farther
than the robing room. In the Chancery Courts the etiquette is not so strict.