On Thursday, 21 November 2019 22:58:44 UTC, Tricky Dicky wrote:
Alternatively could I feed a single 16mm2 cable out of the CU to an
external earth terminal strip and connect the three bonds to it?

I don't think so, as that would mean that the Main Earth Terminal would be inside the CU and the gas and water bonds would be jointed at the external strip which isn't allowed.

If you connect the main earth bond to the terminal strip, then the gas/water and the CU to the strip, the strip becomes the MET and the gas/water bonds are unbroken and that would be compliant.

Owain