Art Nouveau Ladies Wristwatch

This is a watch from my mother, she doesn't remember where it came from. It is a mechanical movement (currently not running) with a beautiful face; swiss made written (very worn out though) underneath the 5,6,7. The centre of the face looks to be solid gold, possible hand carved by what I can tell through the crystal. There is a spot to lift the from crystal as well (3 pc. body) but I haven't felt the need to do so yet.

There is the name Banner and 'gold filled' written in what looks to be a maple leaf with the (serial?) number 293471 below it on the back of the casing. There is an 'E' in the leaf. There are markings that seem to show it was serviced twice by different jewellers, but I only have a 10x loupe so I cannot make out those numbers clearly.

The band is marked G.F top b/r, which I think means gold filled top of bracelet. I see four visible red jewels in the movement, it is a 15 piece movement. The style makes me think it comes from the 1920's but any clarification would be helpful.

Looking for any expertise pertaining to the origin, a better guess at the year it might have been made, and whether or not Banner is the company it was produced by. There looks to be quite a bit of corrosion on the front, so I'm wondering it is worth repairing/cleaning up. Any information is appreciated!