On Sat, 22 Apr 2017 10:50:44 +0100, Ivor Nastychestikov wrote:

Bathroom has hot and cold water pipes, electric towel rail and an
electric shower, what bonding is required?

Is everything RCD protected?
Has the incoming water pipe (and gas/oil) got bonding in place?
If so, then it is likely that there is no need for any Supplementary
Bonding.

If no RCD, or not all circuits in the bathroom are RCD protected, then
you should have Supplementary Bonding between exposed conducitve
metalwork, and the CPC of the circuit(s) in the bathroom.