I cant open Percy's link, but I believe his socket is similar to the one I have; in this photobucket link:
http://i480.photobucket.com/albums/rr170/ocsid3/IP44Socket.jpg
I got this some years ago at a French Marina's chandlers after see them in use, mainly by the Dutch, on the continent.
My require was and remains to get a 90 deg socket as the EHU connection is in the awning and the normal UK ones are a curse sticking out.
I have though used it for electrical equipment, BBQ & cooker in the awning, but I hasten to add via a RCD. Clearly using a French plug.