srw
It's a bit more complicated than that...
I was assured by my late father, born in India when under the Raj, that this was true.
POSH stood for Port Out, Starboard Home.
Going out from from the Blighty to India the expensive cabins were on the Port side of the ship, which when one entered foreign climes (anywhere east of Gibraltar) the cabin would be on the cool (northern) side of the ship in constant shade.
The cheap cabins, such as those where my late father was put as a boy on his way to and from school once a year, were on the south side of the ship, where you cooked as soon as the sun came up. It meant the south facing cabins were unusable during the day, which forced everyone on the cheap/sunny side into the shade of the common areas during the day, the POSH people however could stay in their cabins
So people going on the regular lines between the centre of the Empire and the colonies in the east were happy to pay extra to travel POSH
[QUOTE 5024861, member: 259"]I was told something like this by my big brother who was a navy officer, but then I read it was all a load of rubbish in Wikipedia. Ho hum.[/QUOTE]
It's a load of rubbish.
There's a good and systematic debunking of this perennial myth (which was doing the rounds online well over 20 years ago) on Snopes:
https://www.snopes.com/language/acronyms/posh.asp
The most likely etymology is from Romany.