The treatment of the wood near the raised sections behind the detonators on your gun is not typical for English guns. Further, your gun would appear to be missing the disc set strikers seen on the Webley.
It might be splitting hairs, but, not having identical features would point to a home produced action, rather than a sourced action, bought raw and finished.
I doubt we can know for sure with what we have to go on.

Best,
Ted