Incidentally, a quick look at my meter tails reveals that although the
tails
between the fuse and meter are coloured black and red the meter tails are
both grey - only being identified with a 1" bit of coloured electricians
tape wrapped around them. Is this acceptable?

The red and grey wires are not your property. They may be smaller than 25mm
and it is not uncommon to see 10mm cables between the meter and 100A fuse

I'm planning to change the
CU soon, and will use the opportunity to chnage the tails for properly
coloured ones if the current grey ones are not compliant.


The grey wires are about as compliant as you can get.

Adam