Here is a plain & simple French watch from around the late 1950's. Although the face has a little "peppering" from age, the case and overall condition shows it was likely to have been somebody's "Sunday go to church" watch.
It has a Cupillard 233 2nd generation "tractor engine" inside, and it came with an obviously non original GP mesh, which actually quite suits it, so it's staying on for the time being. I can find nothing about Invex as a watch brand anywhere, other than a photo of a 1960's Invex diver.
If any other lovers of the obscure have come across one before do please let me know.