W.F.S B199 MKIII Rare. The leather case is made by T.A.R S&W ltd and has this stamped plus B199 in pen. Uncertain as to aging this as i cant find another model, but as William Ford Stanley started production in the 1850s ,and other similar ones and they're cases date from pre WW1 - i would say from Pre WW1 - end of WW2.
eBay