The zither-banjos stamped on the heel "Made by J. Newel, 402 High Street, Manor Park" S London were in fact made by Windsors.
They were the standard "shoulder" model made by Windsor, sold at the same price, but without the Windsor name on them minus the '“Castle" nameplate in the centre of the back of the hoop.
Newell was a successful player and teacher.
Do you have a pre 1940's banjo by this maker? can you supply us some images?