I have followed with interest your topic. I am related to George Frederick Whitby and have also been trying to find out any information on him and his Guns.
About 18 members of the Whitby family were either gun component makers,gun engravers, gun case makers etc. They were located in the gun quater of Birmingham from 1841.
G F Whitby and his uncle H A Whitby appear to have been full "Gun Makers" and produced the completed Gun.
George Frederick Whitby moved to work in London and I do have a picture of him.
I would appreciate any information or images of guns etc on any of the Whitby gun makers.