PGW uses abbreviations of this kind quite often, mostly in Bertie's speech. It's all affectation, of course, but cleverly done. The trick here is to shorten an expression so familiar, that it will be natural for a reader to turn shorthand into longhand again, and so not to get angry with the narrator. "I couldn't believe my eyes" - right? "Eggs and b.", "whisky and s." are often consumed by Bertie, and the expressions are used just as often. Sometimes PGW ventures further. My favourite is "Old Pop Kipling never said a truer word when he said that the f. of the s. being d. than the m." (Without mentioning the author it would be a puzzle, it is funny only because the quote is so well-known.)