I thought i found out what it was from because there is a picture on thunder and lightnings page of a gnat F1 cockpit and the ASI looks identical, but then i was told that the Gnat didnt fly until 1955 and my ASI is from 1951, so it cant possibly be from a Gnat,

I may have been manufactured in 1951, but it’s entirely possible that instruments such as these sat on shelves in store for several years before installation in an aeroplane.