I want to put a socket outside to plug our patio water feature into (gad
that horrible, still at least it's not decking!).

The proper way to do it is obviously to put an RCD protected spur in,
and a proper waterproof socket. But of course this would require Part
P hoops to be jumped through.

But, right near where I want it is a double socket we never use because
it's stuck behind furniture. This is protected by the whole house RCD,
but it would be nice to have a local one.

Is it against the rules to drill a hole through the wall, mount a
waterproof socket outside, run a flex (rather than cable) through the
hole and put an RCD plug on in? Then squeeze something that won't
attack the flex into the hole to keep the wind out. Obviously this is
something of a bodge, but it's quick, easy, cheaper (why are RCD sockets
many times the price of RCD plugs and plain sockets?) and Part P immune.

In fact, getting silly, is it legal to take the plug off the pump, run
the flex through a hole in the wall and put the plug (or an RCD plug) on
and just plug it in inside when necessary?
--
On-line canal route planner: http://www.canalplan.org.uk

(Waterways World site of the month, April 2001)