baz wrote
You should have a test point on your gas valve in your boiler.

Out of interest, when you perform a gas pressure test on the whole installation
which valves should be open or closed? Specifically, after charging up the
pipework are you supposed to close the main valve or leave it open? And what is
the criteria for pass or fail please?

I found slight pressure deviations when the main supply valve was open, which
disappeared when I closed it. Then I thought I'd discovered a major leak until
I remembered it was the permanent pilots on our old cooker. As you can tell,
I'm not much of a "competent person" when it comes to gas fitting 8-{/

Peter