Vintage Advance/Retard Lever Identity ?

[brithorby]

Hi All,
I have a nice, long arm (80mm radius) single l.h. Handlebar Control, with an unusual maker's mark stamped on the axial Pivot Bolt hexagon head-face. The Letters are superimposed,so the order is uncertain, but could be J S & D. The "&" is very small and neat. Any ideas what these letters stand for ? I am familiar with Amal, Amac, Bowden,Doherty but not these 3 initials.
Thanks
Rex Acme

[rogerwilko]

Jones made wheel rims, maybe they dabbled in other parts too?

[cardan]

At one time - I don't know when - the full name of Doherty was J. Doherty & Son.

A photo of the lever might be useful.

Leon