Please help,

I inherited my Grandfather's Seamaster years ago but to be honest I didn't appreciate what it was.
I'm now in a better position to have it restored but I don't know which model it is. I've found pics of similar models, some De Villes look nearly the same, but they have slimmer buttresses and don't have the number 12 on
It came on a chain like bracelet in stainless/gold plate similar to the Mercedes watch in the 3rd photo but the plating was very worn so I had the leather strap fitted.

 

My suggestion, to truly confirm what you have, is to take it to a watchmaker to have it opened up so you can take a clear photo of the movement and the numbers in case back. Once you have the numbers, google them and see what you find. Post the photos here and, through your research and the members' feedback, you'll know more about the watch than you probably ever wanted to.

 

There appear to be significant issues with your watch. It is missing the bezel, the dial has been refinished and the movement seems to not be seated properly in the case. Your best bet is to get it to a watch maker and let them open it and see what you have.

 

Omg, that doesn't sound good! Tbh I don't remember it having a bezel and I knew the movement was loose in the case. There's quite a few marks on the case where it's been amateurishly opened previously. I couldn't ever part with it and it's not really about me wearing it as it's a little small for my wrist but I see it as an heirloom so was wanting to look into having it refurbed. I'll try and get it opened up this week. Thanks for your help.

 

Could be onto something there Kyle, found one that looks similar except black face and no seamonster on the back.