A British Ford part part that often turns up on Australian Ebay as a Model T fuel cap, they survived as a non vented and some times having a ford script on it, radiator caps, pre and post war Fords. Maybe it can be worth more if it's a T part!
That looks like the gas tank cap on my 27 Roadster & 27 tudor
Non vented caps are their own reward. ;0*(
Some are plain, some have a cast-in raised Ford script, some have an engraved Ford script and others have a cast in ENFO script, presumably for English Ford. All will work if a small vent hole is drilled in them.
Allan from down under.
The original vented American made caps have the factory number sometimes on one of the wings. Never have seen a Ford script on one. BTW, they used this style cap in 1925 also. All the ones I've seen are pot metal, and most can't be used because of swelling.
?!? Interesting how "pewter" alloys seem to self-destruct with age. 50+ years ago caps like this and rear-axle thrust washers were plenty sound at age 40. Not so now they're 90 and over !