This whole house really is a botch-job. I noticed when we first moved
in that using the microwave and electric oven together caused the
lights to *really* dim. Checking it out, I found the whole kitchen
(including electric oven, sockets and lights) is run from a single
piece of 2.5mm standard ring cable straight from the fuse box. Arrgh!

And of course now it would be legal for you to leave this as it is, but not
to fix it without getting the installation tested! Politicians are plonkers
!

Peter Scott