Crompton 40w blue externally-coated lamp

A nice old Crompton lamp I found on Ebay. It seems these old 1960's Crompton "Colourglazed" lamps (as they would later come to be known) used some very interesting and vibrant colour coatings. This is one of the purest blue-looking lamps I have (when switched off). I also have a green version this age which interestingly looks dark green when off.