An “Unknown Englishman” murdered outside Rome by fleeing Nazis was a secret agent who had been landed by submarine to organise anti-Fascist resistance on Sardinia, a historian claimed yesterday.

The officer, whose anonymous grave lay in a wood dedicated to victims of a 1943 massacre, was named last month by Second World War veterans as “Captain John Armstrong”. But they cautioned that this could have been an alias and appealed for those who might know the truth to come forward.

Yesterday it was claimed that “John Armstrong” was Gabor Adler, a Special Operations Executive (SOE) agent code-named “Gabriel”, who was landed in January 1943 at Cape Sferracavallo, in German-occupied Sardinia. He was captured almost immediately however, together with Salvatore Serra, an Italian Carabinieri (paramili-tary police) officer who had defected to British forces while serving in Eritrea. The pair were found to be carrying a list of Sardinian antiFascist activists whom they hoped to recruit for sabotage operations, including Salvatore Mannironi, a Catholic antiFascist, who was arrested and interned.

Mannironi’s son, Domenico Mannironi, a lawyer in Nuoro, Sardinia, said that he had tracked down “Captain Armstrong’s” identity in SOE papers held in the Nation Archives, at Kew. “After the war my father became a Christian Democratic deputy and served as minister of the merchant navy before his death in 1971” he told The Times. “He spoke little about his wartime experiences”.

He said that SOE files on his father and on Emilio Lussu, a leading Sardinian antiFascist partisan who died in 1975, identified Captain Armstrong as Gabor Adler, described by SOE as “a man of astonishing courage” who had swiftly become a “first class radio operator”.

Colonel Tom Huggan, a retired army officer and historical consultant to the British Embassy in Rome, said that the Embassy was now trying to track down Adler’s birthplace and any living relatives. He said the name suggested Hungarian origins, although SOE records indicated his mother was either British or Italian and that his father was “a naturalised British subject of Italian origin”.

The capture of Captain Armstrong and Serra with a list of partisan recruits may have been a deliberate SOE “double bluff” designed to fool German intelligence into believing that forces gathering in North Africa were preparing to land in Sardinia. Instead, the Allies invaded Sicily in July 1943.

Mr Mannironi said radio messages between Captain Armstrong and SOE supported this theory, as did the fact that the submarine from which he and Serra disembarked had sailed from Algeria. At the end of the war Serra, who survived the conflict and died in 1974, told SOE interrogators that he and Captain Armstrong had pretended to collaborate with their captors to avoid being executed.

After his capture “Captain Armstrong” was transferred to a Regina Coeli prison in Rome and then to Gestapo headquarters in Via Tasso. When Allied forces entered the capital on June 4, 1944, he and 13 other prisoners were taken in a lorry by German forces retreating northwards up the Via Cassia.

Near the Rome suburb of La Storta, the fleeing Germans offloaded their prisoners, herded them into a wood, forced them to kneel and then shot them in the back of the neck. A monument on the Via Cassia records the massacre, and trees planted at the site carry plaques bearing their names – except for one, which simply reads, “The Unknown Englishman”.

Harry Shindler, spokesman for the Star Association, which represents veterans who fought in the Italian campaigns, said that Father Hugh O’Flaherty, a Vatican priest who ran a network supporting escaping Allied POWs, had bargained Captain Armstrong’s freedom in exchange for protecting the family of Pietro Koch, an Italian Fascist leader who was preparing to flee Rome. The deal had fallen through because, fearing a trap, Captan Armstrong had to the last refused to reveal his true identity.

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