Andrew Charles Ltd has dated this Silver Half Hunter Pocket Watch to the 1930s.
Swiss signed 'J.W. Benson' 15 jewel jewelled lever movement with bi-metallic balance. The 'J W B' silver case bearing a London hallmark for c1936 and numbered 656224.

Case diameter 50mm.
J.W.Benson was founded in 1847 in London by brothers James William and Samuel Suckley Benson, this partnership was dissolved in 1855. The factory was bombed in WWII and they ceased manufacturing. Mappin and Webb bought them out in 1980.
Andrew Charles Ltd has dated this Silver Half Hunter Pocket Watch to the 1930s.
You can view the stock and full dealer information on the Andrew Charles Ltd Profile Page