My wife bought me an apparently vintage Heuer for an engagement gift. It is a mans automatic wristwatch and the seller, who is more of a jewellry guy than a watch guy, told her it was made around the late 40's. Is there any online reference to the automatics I could use to identify it?

It is a mans automatic wristwatch with arabic numerals and a case diameter of about 31mm. The dial could have been silver or white, or maybe off-white, the numerals appear to be gold coloured and there is a Heuer logo with "Automatic" underneath in the top half of the dial and "21 jewels" in the lower half. Unfortuantely it leaks a lot so the dial is not in the best shape.

It has a screw back with "swiss made automatic antimagnetic" and "waterproof all stainless steel incabloc" around the edge of the back. The number 2550265 is stamped in the back, would this be a serial number?

Ideally I would like to get the watch repaired so that it doesn't leak as currently I can't even wash my hands with it on. However, before that I would really like to be able to know what it is. Any help very gratefully received, thanks.