eightbore, My Purdey is not a hammer gun. It's a sidelock bar action "Best" gun. Made 1906. Has sideclips and weighs in at 7lb /12oz. I was curious about the fact it had what appears a regular game style rib.
I contacted Purdey via email, always had good luck doing so. You can go to their web sight and register as an owner and possibly ask your questions there.
Anyway they replied back that indeed it was specified and built for pigeon shooting.
Unfraternally I got in to pigeon and Helice late for my area of the country. Shot pigeons here in N.C. close to the house a couple of times. My home club (Deep River Sporting , Sanford , N.C.) had the old ZZ bird set up for awhile till the controller broke.
There are now at least three clubs in the N.C. / S.C. now throwing helice. Hope to be traveling in the spring with the old Purdey to give it a go.