Kitchen fitter has mentioned that it may not be allowed to have an
electrical socket anywhere where it could be reached while someone had
their hand in the kitchen sink.

I guess it depends how long your arms are, but these seems to preclude
providing sockets on some otherwise very usable bits of worktop!

e.g. was going to put the kettle in the corner between the sink and
the wall, but can't see how to power it if this rule applies.

Is this at BCO's discretion?!

Cheers,
David.