AnthonyL wrote:
OUr gas meter is at high level in the pantry of our bungalow. There
is an airbrick at about 4' height which introduces quite a lot of cold
air and dust/dirt and SWIMBO would like to block it off.

Google isn't clear. What and where are the regs applying to it and
more simply can I put a piece of card in front of the airbrick?

You can take the airbrick out and plaster over it, unless you want
ventilation in this area for some other reason.
Gas meters have no need of ventilation, food used to before proper
refrigeration, and this is what the pantry was originally built for, along
with it's airbrick.