Nice clean example. I'd say Accutron 259. Full advert here.
1972 Bulova Accutron 259
Looks to be a very good match, Geoff. I agree this is an Accutron 259. I do believe it is a 259, and not 239 as you posted.
I think you're right Ken - I updated the comment, thanks.
1972 Accutron "259" looks like a good match to me as well.
1972 Accutron 259