TT:
The group you may have in mind is called 'The Vintagers', aka 'The Order of Edwardian Gunners'.

VintagersWebsite

I have been a member of the Vintagers Down Under (Australian Chapter) for several years, though I am unable to attend regular shoots due to distance (>3500km)!

Vintagers Down Under

The emphasis is on shooting period-pieces from the Golden Years of the British shotgun. Most popular here are top-lever hammer-guns in SxS configuration. Vintage rifles are also used at some meets, or in conjunction with the Big Game Rifle Club.

BGRC

Many of us are members of both organizations.

Many of us hunt with our vintage doubles too, so we know first-hand the immense satisfaction gained from bagging game with these marvellous old guns. Congratulations on your deer, TT. Nice work! ...and first of many I trust!