I've heard Purdey's made twist barrels as late as 1928 for special orders.
My late friend Wil T. had a 10 bore Westley Richards that he sent 'back' to England for a fitted case as well as a going over as it was a bit stiff. It was returned to him, in fitted leather bound case & re-proofed for nitro loads as it was in "new" condition, and from the 1880's. It was choked, but I don't remember the constrictions - not much, maybe IMP/Cyl and MOD.
Beautiful gun. Wil used it for the trap turkey shoots in Smithers, in the late 70's and 80's, shooting 1 1/4oz. of shot. It would hammer the birds as Wil only used BP loads in it, in 2 7/8" cases(quite sure on the length).
The shot string was literally non-existent, and threw FLAT patterns, a wall of shot.