On Mon, 01 Apr 2013 18:31:04 +0100, Tim Watts wrote:

An option involving no wall bashing would be to blank off the old
socket box, and use it to hold a joint for the ring and the spur - so
two cables emerge from the box at surface level and you run these
around a couple of surface mounted sockets.

Or just cut back the conduit that is feeding the current double socket,
fit another double socket, join those as a ring and take the existing
spur from one of them,

--
Cheers
Dave.