it is a smiths v308 from the 1950s. it was used on the v bombers, i.e. valiant victor and vulcans. it has the jaeger le coultre 8 day movement.
i had one, i put it in the dashboard of my 68 dodge dart. i used it for one week and four days and the mainspring broke.
i had it up for sale on ebay for a dollar for over 6 months and no one bought it. not sure where it is now.