Thank you both for informative responses.
In the link supplied by Less I did read about the 'supplementary bonding/earthing' in bathrooms - that link explains why my radiator
had one, and why my gas meter
has one
Retlaw's response makes sense to me too.
The type of connection to earth that is recommended for possible health benefits, is a flow
from the earth, as well as the discharge of static to the earth. I suppose I could get the same effect by sleeping clutching the nearest water pipe
- but that isn't practical.