Which model is this?

Australian cases usually had Handley's markings where as this one doesn't.

To @PickPocketWatch , where are you located and what can you tell us about the history of the watch?
I also agree that it may be mid 1950s, maybe earlier (say 1953/1953) but as you've hidden the full serial number I can't give you an exact date.

Hope you've been enjoying our great weather for the last week or so then 😉.

If the watch is Australian as @X350 XJR noted, then it's a good chance the movement was imported and then fitted to a locally made case (most probably by Handley who were based in Abbotsford, just down from the Skipping Girl sign in Victoria street).

I was pulling you leg about the serial number, it makes sense that it's mid 50s.

As it was on the cusp of Omega actually naming watches (e.g. Seamaster in 1948), and the effects of WW2 still hurting the Australian economy, it may have been one of the movements shipped to Australia for casing before that practice was overtaken by Omega importing fully assembled watches themselves.

It looks to be a nice watch and with a gentle clean, a new crystal and a movement service it would be a pleasure to wear.

Cheers
Jim

Forgot to add. Omega only had "models" from about 1948, starting with Seamaster.

There were exceptions such as those from the 1920s/1930s, but there were not that many of them.

For example: Acribes - 1930s, Alcaios - 1940, Argos - 1930s, Dedalos - 1930s, Euroos - 1933, Foibos - 1933, Filenios - 1930s and Firmus - 1930s.

There wasn't many of them were there 😁.