Green’s Dictionary of Slang

rag n.2

[‘The familiar name of the Rag, by which it is generally known, was invented by Captain William Duff, of the 23rd Fusiliers. Coming in to supper late one night, the refreshment obtainable appeared so meagre that he nicknamed the club the Rag and Famish’ (Nevill & Jerningham, Piccadilly to Pall Mall, 1908); note also the less well-known Rag: the Raglan Music Hall in Leather Lane, off Holborn WC2]

an abbr. of the Rag and Famish, the Army and Navy Club, London.

[[UK]R. Nicholson Rogue’s Progress (1966) 67: he was since been found [...] playing even for coppers at a place not inappropriately designated the "Rag and Famish’, in a turning out of Cranbourn Alley].
[UK]E. Yates Broken to Harness I 69: From the Doctor’s I went to the Rag and found Meaburn there.
[UK]Punch’s Pocket-Book (1878) 172: There’s a Major I know who belongs to the Rag [F&H].
[UK]Lovett-Cameron Neck or Nothing i: The very smartest and best-looking man to be met with between the Rag and Hyde Park Corner [F&H].
[UK]Daily Tel. 19 Aug. 5/2: The genial ‘Rag’ welcomes the sympathetic spirits of the Naval and Military with open arms [F&H].
[UK]‘Pot’ & ‘Swears’ Scarlet City 23: Being as much at home at the ‘Rag’ [...] as he was on any one of Her Majesty’s Ships.
[UK]E. Pugh City Of The World 57: The amount of leisure, flavoured with whisky, that they get through in the course of a day would make a half-pay officer at the ‘Rag’ think he had struck the millennium.