This is a PL 55 much the same as the PL53 tank capacity 2.5 pints against 1.75 pint in the PL53. Has a rather distinctive handle on this one. The control cock on this one is rather unusual its a brass knob stamped Tilley Lamp B and a little retaining grub screw only one i have seen like this. The pump tho raised lettering which usually has a baynet one way valve this one has the next style of valve in the base the hex with two holes mid 30s style.
