Roger Mills wrote:

It's not a bathroom per se in that it doesn't contain a bath. It's an
en-suite facility which has a toilet and bidet one end, and a wash basin and
shower cubicle the other end. Does that make any difference?

No, the same zoning applies.

The relevant bit looks like http://www.mills37.plus.com/en-suite.JPG

Ah, that's useful. The simplest thing would be to take the cable down
the wall in the RH corner, if poss, as that's more than 600 from the
shower cubicle, i.e. is in Zone 3. Otherwise, is the visible part of
the shower enclosure on the left fixed or movable, and how high is the
fan, above floor level?

The pull switch on the ceiling is for isolating the shower pump. It used to
be fed by the 6mm cable but is now fed by a fused spur off a ring main. You
can see the 6mm cable lying across the small hole I have made in the
ceiling. It would need to be chased into the wall, and then go out through
the wall just to the left of the fan. [It needs to come down to this level
to get below the fascia on the outside]. I don't know what zone that would
be. Please advise!

Zone 2, I suspect, up to a height of 2.25 m, then Zone 3 above that.

What is the reason for not having any cables which are on
their way elsewhere - sounds a bit OTT?!

I guess the thinking is that it's not obvious that it would be there, as
there's no electrical equipment in the room to give a clue to the
presence of a cable. The principle is to keep all non-essential cables
out of the the wet areas, thus avoiding danger when you decide to drill
through the wall while standing in the shower... It is a bit of a pain
in this case, although it looks as if chasing in to 50+ mm deep might
not be too difficult, if that is necessary.

I presume a new direct SWA run from the consumer unit to the garage is
out of the question.

--
Andy