Cars with 3 pin electrical socket?

[TooMany2cvs]

I've got a factory-fitted 230v mains socket in one of the fleet - 1988 VW - which works just fine. It's a two-pin-plus-earth Euro socket, but there's a three-pin UK adaptor plugged into it.

Mind you, it is a Westfalia camper, and it does only work when the hook-up's plugged in, along with the fridge's 230v element and the charger for the leisure battery...