The push fit switch may have been of MGB origin. From the 76 facelift, the B had a push fit sender in the header tank. It was later modified with a spring clip which located under the sealing rubber and held it in place. I held mine with a blob of superglue until I got a clip sorted out. I actually fitted one of these to my Gilbern Invader header tank in 1990 and I can remember the sweat involved in cutting the hole exactly the right size. It worked though.......
(MGB trivia buff).
