Drew,
Thank you so much for that very detailed and prompt response!

The original date bracket of 1896-1904 fits in with the information given by Parabola above; namely, its predecessor, 6182, was shown in January 1901.

I hope that it will be used in anger by my son next month; I’m left handed and left-eyed and prefer to shoot 20 bore these days. A lighter gun and certainly a lighter cartridge bag!
Tony