FWIW I think the two 1950s watches most commonly associated with Bonklip (or B-type) bracelets are the Rolex Bubblebacks and the West End models.
Perezcope says it's an old / obscure / obsolete brand and that it has subseconds so (assuming he's right) my money is on a West End retailed Sowar Prima
https://www.vintagewatchstraps.com/westend.php
(NB the normally excellent David Boettcher repeats the common mistake of saying "CSI" = Civil Service India when in fact it's Canteen Services India, a sort of NAAFI / QMS)
Well, we'll see, Possibly.