POSH a Maritime Term?

POSH Spice of the Spice Girls

‘Port out, Starboard home’  A popular theory holds that the term Posh is derived from the initials of “Port Out, Starboard Home,” the cooler, and thus more expensive, side of ships traveling between England and India in the mid-19th century. The acronym POSH was supposedly stamped on the tickets of first-class passengers traveling on that side of ships owned by the Peninsular and Oriental Steam Navigation Company.