There was little of the archetypal hero in Roger Landes’s appearance. Of medium height with the air of a shrewd but possibly accommodating bank manager, he spoke English with a decidedly French accent. It was his fluency in French that first drew him to the attention of the Special Operations Executive (SOE). He was to fulfil the expectations of the SOE authorities not just as a radio operator, for which he was recruited, but as the leader of an SOE circuit in German- occupied France.

At the time of the 1938 Munich crisis, he was living with his brother Marcel in Paris, their parents having moved to England after the failure of their father’s jewellery business in the Depression. Born in Paris, the son of a British subject, Roger had dual nationality, so joined his parents in England and secured a post with the architect’s department of the London County Council as a quantity surveyor. When war came, this employment delayed his call-up but he joined the Royal Corps of Signals in March 1941.

His French and familiarity with France having been noted, he was interviewed for training as a radio operator in the German zone of occupation and given five minutes to decide whether or not to volunteer. He agreed and began specialist radio training and instruction in the use of plastic explosive. After parachute training and commissioning, he and another agent were dropped southwest of Orléans on October 31, 1942. His instructions were to join the SOE “Scientist” circuit in Bordeaux.

His codename was Aristide, confusingly shared with other agents, and initially his responsibilities were to maintain radio contact with SOE headquarters in London, working from varied locations and on irregular schedules to avoid detection. The low-lying Bordeaux region was unsuited to radio transmission, but he found an unoccupied bungalow on high ground ideal for his purpose. Shortly after establishing himself in Bordeaux, Landes was introduced by the leader of the Scientist circuit, Claude de Baissac, to the local head of Organisation Civile et Militaire, André Grandclément, an association that subsequently was to have dire consequences.

Anxious to avoid compromise of his bungalow transmission site through over-use, Landes set up three more and used all four to no discernible pattern. Then, in August 1943, Claude de Baissac was flown to England by a Lysander aircraft for consultation. Landes was promoted to captain and appointed leader of the Scientist circuit.

The circuit extended its range of agents under his direction, and the chance arrest of one revealed the involvement of Grandclément. First arresting his wife, the Gestapo put it to Grandclément that France’s real enemy was communism, so why did he not join the war against the threat from the east? Whether the Frenchman was taken in by this (he was of strong right-wing opinions) or by his wife’s being in Gestapo hands is arguable. He agreed to reveal Resistance arms caches in return for his life and that of his wife and, on being let go, promptly informed a senior Scientist agent of this intention.

Landes was witness to this event and his instinct to shoot Grandclément on the spot was restrained only by the presence of the agent’s wife and daughter. Through some prompt communication, Landes and the Scientist agent were able to get a substantial proportion of the arms away from the caches before the Gestapo reached them, but the whole circuit was by then at serious risk.

With Grandclément under Gestapo control, Landes knew his own arrest would be only a matter of time so he dropped out of sight and changed his alias to Roger Lalande, a real but absent person with authentic papers and registration. The Gestapo arrested other Scientist agents, however, leaving Landes no alternative but to cut all connection with the circuit and Grandclément, while informing London what had occurred. He was instructed to make his way out through Spain.

The journey was physically demanding and fraught with bureaucratic hazards. After a period in a Spanish prison, he reached Gibraltar on December 31, 1943. On return to England, suspicion in the SOE hierarchy that he might also have been “turned” by the Gestapo led to his interrogation until able to prove his loyalty. With the Allied invasion of France only five months away, SOE was acutely security sensitive and preoccupied with preparations to bring much of the French railway system to a halt, to curtail the movement of German reinforcements to the intended Normandy beachhead.

After re-briefing, Landes and a radio operator were dropped on the night of March 1-2, 1944, to a Resistance reception party near Auch in southwest France. A strong wind caused him to land awkwardly and sprain his ankle. Two weeks rest and medical attention in a safe house restored his mobility and enabled him to return to Bordeaux. By the end of March he had made contact with the survivors of the Scientist circuit and had begun to call for arms drops, but Grandclément was still active.

The Frenchman was persisting in his efforts to turn the Gaullist FFI Resistance against the overtly communist FTP throughout the region. Despite this, Landes restored his circuit and gave instructions for attacks on rail and other communications immediately after the invasion on June 6, 1944. The security of this action could not be risked, so when informed that Grandclément, his wife and bodyguard had fallen into the hands of the resistance near Arcachon he at once went there to take charge. Grandclément admitted his treachery and with Bordeaux still in German hands, Landes had no option other than to order the execution of both the Grandcléments and their bodyguard.

After the German evacuation of Bordeaux and the establishment of a provisional government under General de Gaulle, the French leader visited the city — in which he enjoyed no great personal popularity — on September 17, 1944. Landes was presented only to be greeted by the words: “You are British. Your place is not here.”

Landes was awarded the Military Cross for his first period of SOE service in France and a Bar for his second. He was also appointed to the Legion of Honour and awarded the Croix de Guerre with palm. He was advanced to Officer of the Legion of Honour in 1992 in recognition of his wartime services to France.

Roger Landes was the second of three sons of Barnet Landes, whose grandfather had emigrated from Russian Poland in 1848 to avoid conscription into the Tsarist army. His father spoke English only hesitatingly and preferred to live with his Russian wife in Paris. Roger was educated in Paris and graduated from L’École des Beaux Arts in the year after his parents’ departure for England.

He married Ginette Corbin, daughter of the French Scientist agent Charles Corbin to whom André Grandclément had revealed his intention to betray the arms caches to the Gestapo. She died in 1983 (obituary March 12); Landes married Margaret Laing in 1990. He is survived by her and a son of his first marriage.

Roger Landes, MC and Bar, officer of the wartime SOE, was born on December 16, 1916. He died on July 16, 2008, aged 91