The message
from "Grumps" contains these words:

Had a single storey rear extension done a few months back and this
obviously
included an extension to the mains ring. Is it true that wiring regs
require
any socket that can be potentially used outside (extension lead) to be RCD
protected?

Yes, but if your existing CU already has RCD protection on the sockets
this is considered OK.

--
Skipweasel
Pay no attention to that man behind the curtain.