Hello Trev,
I do happen to own a virtual clone of your A&N.
I have on my desk #68327 with Webley # 98638. It's peculiar that the A&N #s are 52 off while the Webley #s are ~15,000 off. So much for predictability...
The action is the same and the engraving is very similar. This model is not depicted in my 1922 Webley catalog, but it is definitely a Webley action.
My chambers measure very close to 2 5/8", but that does not mean that your gun's chambers are not originals.
I will ask for the records on my gun as well.
Best regards,
WC