Green’s Dictionary of Slang

edgar allan n.

[rhy. sl. = po n. (1); ult. US author Edgar Allan Poe (1809–49)]

a chamberpot.

[UK]Galton & Simpson ‘And So To Bed’ Steptoe and Son [TV script] Albert: Where do you put the Edgar Allan then? Assistant: The Edgar Allan? Oh, I see. We naturally assume that most people have separate arrangements for that sort of thing.