From The Internet Gun Club there are several Wilkinsons. You could try and register there and ask them about your particular gun. They have been able to get information on several guns for members and registration is free. They also have access to the records of the Birmingham Proof House.

Best wishes and good hunting!

First Name Last Name 1st Address City/Town
Nock & Wilkinson See Henry Nock
Frederick Wilkinson Castle Street London
Peter Wilkinson 10 Poppins Court, Fleet Street London
Thomas Wilkinson 6 Great Ormond Street, Queen Street London
Thomas R Wilkinson 19 Camberwell Road London
James Wilkinson 10 Ludgate Street 19-21 Brunel Road, Acton London
Edward William Wilkinson 12 & 13 Whittall Street Birmingham
William Wilkinson Gill Yard, Vicar Lane Leeds
James Wilkinson Thomas Street Bristol
Matthew (Matthias) Wilkinson Castle Ditch Bristol
John Wilkinson High Street Tonbridge
T H Wilkinson Thurlstane
Wilkinson Victoria Road Penrith
John W Wilkinson 546 Pearl Street New York
Henry Wilkinson See James Wilkinson of 10 Ludgate Street
G S Wilkinson See Wilkinson Bros. Keeseville
Henry Wilkinson Newburgh
John D Wilkinson Plattsburg
Joseph Wilkinson Bridgeport
A E B Wilkinson Birmingham
Wilkinson & Son See James Wilkinson of 10 Ludgate Street
Wilkinson Bros. Plattsburg
Wilkinson Sword Company Ltd See James Wilkinson of 10 Ludgate Street
Wilkinson Sword Ltd See James Wilkinson of 10 Ludgate Street
Wilkinson's Durham
Antony Wilkison (Wilieson / Wilkinson) Opposite Fountain Well Edinburgh