A nice period shot of a cammy Norton hitched to a sidecar, but what is it exactly? The forks look like early 1930s Webbs to me, without the adjustable dampers and check springs. The 21" front wheel has the drum brake on the left hand side and uses an obsolete speedo drive. The oiltank is of the later wrap-around type.
Roger: "CG366 is a London registration dating from 1930 so it is probably a later picture with subsequent modifications to the various bits"