Here it is, early 1950s:
The movement is a cracker, a rare MST417. Only made for a short time before being replaced by the redesigned MST427. Not often seen in either version, they only appear on the 'bay maybe once or twice a year - almost all of which are 427s. The way you can tell the difference is the extra hole by Roamer in the 417. This is an in-house movement of considerable sophistication, with only 1 crown to set, time and alarm and wind the separate alarm and main barrel. This calls for a 3 position crown and horribly complex setting mechanism. Wonderful - especially compared to the pedestrian AS1475 that was fitted to most contemporaries, this Roamer calibre was on the market several years before the AS calibre - which used 2 crowns, and just several years after Vulcain's famous 120 Cricket.
The really interesting thing, is the back. This back was patented in 1952, and is tuned with those grooves - to give a clear bell like ring. This was difficult for most alarm watches of the period as Vulcain had wrapped up the twin shelled sounding back in patents, and most alarm watches (Benrus, Bulova, Technos, etc etc) had to put up with a dull thudding noise instead of a clear bell. This was Roamer's way around Vulcain's patents. Clever!
I now have both the MST417 and 427 in my collection. A rare combo here in one photograph - possibly the first time so seen on the internet.