Shabby old diver's watch...
...or thin case DRSD 1665 from 1967 with Mark II chocolate / smudge dial?
You could say either or both, but it has significance in any event. Much greater detail and macro photographs may be found here:
https://www.miltonaires.com/7400/thi...5-mark-ii-dial
It's not my watch; we just appraised it for a lovely visitor.
Haywood