It's a VERY early rifle built at Fazakerly(? on a leftover trials body (receiver).
The simplified cocking piece is very unusual, and we wouldn't expect to see a Long Branch pressed safety catch spring either on such a rifle AFAIK.
However the finish is a close match, so perhaps they have been together for a long time. The screw is different from the standard as well.
I see the Enfield "D/E" hybrid mark on the safety catch and that is what we would expect on such a rifle.
Does it have the "waisted" foresight protector, hinged upper band and other such trials rifle features?