Eileen Nearne was a war heroine who, despatched to France as a secret agent during the Second World War, died decades later in obscurity having survived Gestapo torture and a Nazi concentration camp.

She survived through her daring and resourcefulness, escaping from the hands of the Germans to make contact with advancing allied forces.

After an ordeal which left her severely traumatised, she lived quietly for 65 years. Her adult life thus fell into two main parts, the first in the most dangerous circumstances, the second almost entirely uneventful.

She was interviewed and mentioned in books by military historians, one of whom described her as "a real heroine, although a silent one." She was unknown to the general public, spending her last three decades in Torquay, where she did not advertise the exploits which had taken her so close to an early and agonising death.

After she was found dead of a heart attack at the age of 89, she seemed destined to be buried in obscurity by the local council. But when the tale emerged of her part in the Resistance the British Legion and others took steps to ensure she received some of the honours due to her. Mourners lined the streets of Torquay for her funeral on 21 September, including representatives of the armed forces. The service concluded with the Last Post played by a French bugler.

The Legion's county manager, John Pentreath, said the organisation wished to ensure that Nearne received "the dignity and respect and homage that befits a lady of her experience," adding, "It's a staggering story for a young girl. We hold her in awe and huge respect. We are very disappointed we didn't know about her when she was alive – we would have dearly loved to have made contact with her."

Eileen Mary Nearne, known as "Didi", came from an Anglo-Spanish family and was the daughter of John Nearne and his French wife Marie. Born in London in 1921, she was brought up in Grenoble but at the outbreak of war fled with her family through Spain to England. When Eileen and her sister Jacqueline volunteered for war work the value of their fluency in French was recognised and they were recruited into the Special Operations Executive (SOE).

Churchill had set up the SOE "to set Europe ablaze" by co-operating with resistance groups in activities such as intelligence-gathering, espionage and sabotage. He personally authorised the recruitment of women, who, it was thought, would find it easier to escape Gestapo attention. After training in London the sisters were sent separately to German-occupied France, where Jacqueline worked as a courier and Eileen as a radio operator. It was an extremely hazardous business: many SOE agents, both men and women, suffered torture and death.

In March 1944 the 23-year-old Nearne was flown to France in an RAF Lysander aircraft, to be greeted by two French resistance members who said in surprise: "Oh, a young girl. Go back – it's too dangerous." But, ignoring their reservations, she stayed on and transmitted more than a hundred messages over the following five months.

It was a game of cat and mouse with the Nazis, whose radio experts constantly monitored the airwaves for clandestine transmissions. With the Germans despatching fast vehicles when they pinpointed the source of messages, she was constantly on the move.

Professor Michael Foot, a historian who worked with the French Resistance in 1944, said of her role at the time of D-Day, "She was working a secret wireless set from Paris to England. What she did was extremely important. She primarily arranged drops of arms from London to resistors in eastern Paris and around Lille, where they made the French rail network practically unusable by the Germans during the fighting in Normandy."

Nearne later recalled, "I used to go out a lot and have my meals in restaurants alone. It was very solitary. I wasn't nervous but of course I was careful - there were Gestapo in plain clothes everywhere. It was a life in the shadows but I think I was suited for it. I could be hard and secret, I could be lonely, I could be independent, but I wasn't bored. I liked the work. After the war, I missed it."

She added: "When I put my hand on the signal keys, there came a feeling of patriotism. I was pleased that I was doing something. It was perhaps a little emotional."

She used code names and aliases such as "Rose" and "Mademoiselle du Tort". She had at least one narrow scrape, managing to convince a German soldier on a train that the radio she was carrying was actually a gramophone. But in July 1944 Germans arrived at a house where she had just been transmitting, and although she managed to burn her messages they discovered her radio and her pistol.

Although these items were highly incriminating she admitted nothing, maintaining that she was a naive young French girl. She maintained this fiction even when subjected to what is now known as "waterboarding". Her interrogators stripped her and plunged her into cold water, creating the impression that she would drown. According to Professor Foot: "She told them that she was just a little shop girl who had gone into the Resistance for fun. They didn't, of course, believe her but they couldn't get anything else out of her at all."

She was sent to Ravensbruck, the notorious women's concentration camp in northern Germany where tens of thousands of women were killed. These included a number of members of the SOE. Nearne befriended one of these, Violette Szabo. They were planning an escape, but they were separated and Szabo was later shot.

During a nocturnal forced marchto a labour camp Nearne saw a chance of escaping and with two other women ran into a forest. During the nextfew days they were spotted and questioned by German soldiers but managed to convince them they were not escaping prisoners. They reached Leipzig, where they were sheltered by a German priest. Shortly afterwards they made contact with American troops – who were initially dubious about their stories – and Nearne's short but perilous war was over.

Reunited with her sister, she lived first in London and later in Torquay. She never married. Although she was interviewed by historians, she did not generally speak to neighbours of her war record. One Torquay neighbour said: "I sometimes sat and chatted with her. She never talked about herself, only about her cat, who she took in after someone abandoned him."

Her ordeals in the Gestapo interrogation centre and the concentration camp left a lasting mark on her, a pensions tribunal declaring her 100 per cent disabled as a result of "exhaustion neurosis". In 1950 she was found to be suffering headaches, depression, sleeplessness, palpitations and a sense of unreality, a psychiatrist saying she displayed "characteristically schizoid representations". Her war pension was later reduced and eventually terminated, apparently because she moved to live in France for a time. She was later awarded the MBE.

RAF veteran Beryl Escott, author of an upcoming book on the SOE, said of her activities: "It was vital and dangerous work, especially for wireless operators. She was an excellent agent, very imaginative but very unobtrusive – and that is a very important quality."