It is working and I have tested it for 24 hours against my TAG HEUR and it is absolutely accurate. Many thanks for your comments.Welcome to the forum.
Not my field at all, but it has the word 'waterproof' on the back which was dropped at the end of the 60's but has a date window - uncommon at the start of that decade - so I'd guess at mid 60's.
But a Citizen collector - or anyone with more knowledge than me - may know more.
If its working its a nice find. A new crystal would transform it.