Poshly hevelled.

A correspondent — Madame Quince, in fact — suggests ‘Hevelled’ or perhaps ‘Shevelled’ as a pleasing back-formation: if one can be ‘Dishevelled’ then one can presumably be ‘Hevelled’. She imagines going to a posh do hevelled in her best clothes.

It seems that the derivation of ‘Posh’ from the acronym ‘Port Out, Starboard Home,’ chalked on the luggage of the more privileged ship passengers from England to India and back, to ensure cabins out of the hot sun in colonial days, is also spurious, with little evidence to support it. It is an example of ‘Folk Etymology’; an ingenious but false explanation like that for ‘Marmalade’.