As the Iron Curtain descended across Europe, pitching the powerful Soviet Union against Western allies, industrialists and engineers in Germany were working on gadgets that would help spies stay one step ahead of their enemies.

One such device, a watch with an inbuilt hidden microphone made by Germany’s Protona, is up for sale next month at Fellows Auctioneers’ Online Watches and Watch Accessories sale.

The Protona spy device, which has a pre-sale estimate of just £140 to £200 ($185 to $260), was created as a chronograph wristwatch.

On the side of the watch’s case there is an insert with a wire which can be threaded up a sleeve and concealed. The wire would then connect to a recording device which would be placed and concealed over the shoulder of the wearer.

The portable device was capable of recording up to an hour of audio.

At 40mm, the steel watch might have been a little on the large side in the 1950s, but still found a lively market with police and intelligence organisations.

Laura Bishop, watch manager at Fellows Auctioneers, explains: “This is the perfect opportunity to own a fascinating piece of espionage and an intriguing watch combined. I can only imagine some of the conversations that this device might have recorded. We have been unable to gain access to the movement of the watch to find out its exact condition, however the dial is intact with no visible marks. History and watch enthusiasts alike won’t want to miss this one. I’m sure it will fly above its estimate.”

The Online Watches & Watch Accessories sale on 8th December will be Fellows’ final auction of timepieces in 2020. The sale is live now, operated in a timed format, and bids can be placed right up until the lot closes on the day.