As received with non-standard (is there a standard for E41s?) painted green hood and painted black handle. Otherwise, I'd say this is pretty-much as was with T-bar pressure release, brass knob and flat-topped pressure gauge. The globe rest is marked 'Patents Pending' which may be a pointer to the date of production. The pressure gauges seem to come in two varieties - flat-top and dome-top. I presume there were two different materials used for these because all the flat-tops I've seen are transparent and still readable whereas all the dome-tops have a pale yellow discolouration on the inside which renders them opaque...
David you're right, the patent pending on the frame is a very important point as regards dating. It refers to patent 540783 which was applied for by Willis and Bates on 10th August 1940 and granted on 29th October 1941. It concerns the design of the frame which allows the control cock to always be in line with it's aperture in the frame because of the multi screw holes in the frame and tank. The only other part that was patented in the first lamp was an improved vapouriser. It would have been very foolhardy of Willis and Bates to start production of their lamps before the submission of an application for a patent. (The patent could have been invalid had they done so) I have seen several E41s marked with the year 1940. Therefore we can say with some confidence that production of Vapalux lanterns commenced sometime shortly after August 1940.
