Pish about posh being P.O.S.H.
From WordOrigins.org

Posh:
This is another word with an apocryphal acronymic origin. Popular etymology has it that posh is an acronym for Port Out, Starboard Home. Supposedly, this acronym was printed on first-class tickets issued by the Peninsular and Oriental Steam Navigation Company going from England to India. The port side on the trip out would have the coolest cabins (or alternately the cabins with the best view). The same would be true of the starboard cabins on the return trip. From this origin, sprang the usage of the term meaning swank, elegant, or fashionable. Unfortunately for this excellent story, no tickets with Posh stamped on them have been found and company records reveal no sign of the phrase.

I feel a cup of tea and an ice-cream van coming on, you know...
( calgacus Non sum qualis eram bonae sub regno Cynarae, Mon 19 Sep 2005, 15:30, Reply)