The 14th Foot. Called Calvert from their colonel, Sir Harry Calvert (1806-1826), and entire, because three entire battalions were kept up for the good of Sir Harry, when adjutant-general. The term is, of course, a play on Calvert's malt liquor. The regiment is now called The Prince of Wales's Own (West Yorks. Regiment).
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894