The original design for this type of stove was protected by Patents Nos. 125923 and 152239 which George S. Marris (hence 'Sirram') applied for in January and December 1919, both being subsequently accepted. Having said that, I think there can be little doubt that the 'Redcap' versions were decades later... There were four versions available:- No. 1 - 1/4 pint, which sold for 2/- (10p) No. 2 - 1/2 pint, which sold for 3/- (15p) No. 3 - 1 pint, which sold for 4/- (20p) No. 4 - 1 1/2 pints, which sold for 5/- (25p) These prices suggest to me an approximate date of around 1955, but I could be wrong. I have the No. 1... (the pricker is just to give some idea of scale) ...which is a piddling little thing you might just be able to boil an egg in.