Very intriguing.

It is an Anson and Deeley Patent gun, but where are the cocking levers that would normally protrude from the front of the action bar (which looks as if it may have been re-machined?).

Was it made as or converted to a lever cocking gun?

The 2 drilled holes are in the wrong place for gas vents.

Do they lead to some sort of tensioning screws in the action ?