Having seduced him, she attempted to poison him, but Minshall survived, and the knowledge he had gained did indeed prove useful to the British in a subsequent operation during the war.

At the outbreak of World War II, he was recalled to duty as part of the RNVR where he had a varied career, including working for Ian Fleming.

In early 1940 he was a major participant in the failed scheme to block the Danube in Rumania to disrupt German oil imports, working under diplomatic cover as British Vice Consul in Bucharest.

Later, in November 1940, leading a joint NID/SOE team[2] Minshall ran Operation Shamrock, where a commandeered fishing smack was used as an observation platform for monitoring German U-boat traffic in the Gironde estuary.

[3] Subsequently, he ran a section at HMS Flowerdown, using direction finding and transmitter analysis ("Z machines") to identify the positions of individual ships.

His second wife was Isolde Llewellyn, his third Janine Paulette Sergent of Lyons and fourth Christina Marjorie Zambra, great niece of the Scottish artist Harrington Mann, with whom he had four sons Peter, Matthew, Luke and Timothy.

But Romania set the scene for the height of espionage activity – when he single handedly pirated a ship from under Nazi eyes and blew up a vital link in German tanker communications.