Sebastian Faulks's fictional heroine Charlotte Gray, who reaches the film screen next week, is a young Scotswoman parachuted into France to work with the Resistance during the Second World War. But before she can embark on her secret mission she has to join an all-female voluntary army corps known as the Fany.
Former teacher and schools inspector Marian Jones knows all about the organisation, for she was a real-life Fany. While she was never an agent behind enemy lines, her work, like that of many of the women in the strangely named First Aid Nursing Yeomanry, was so secret that not even her mother was allowed to know what she was doing. Her job had nothing to do with first aid. Instead, she was part of a wireless signals team whose activities were crucial to the flow of wartime intelligence.
Today, at 76, her loyalty is undimmed. "I loved the Fanys," she says fiercely. "I would have loved to have been able to stay with them and make it my career."
At 16 she had never heard of them. She was then Marian Pritchard, a schoolgirl who had been evacuated to Fowey in Cornwall from Plymouth, and was staying in an army major's house when a Fany came on leave. "I thought, 'What a nice person. What a nice uniform. If the war lasts long enough I'd like to be a Fany, too'."
As a grammar school girl she was not typical Fany material. Many were upper-class girls from posh boarding schools - adaptable, valiant and able to keep their mouths shut. But a year later Marian was in the nice khaki uniform with a Sam Browne belt and peaked cap, being trained as a wireless operator to send and receive messages from secret agents in occupied Europe. She served at Signal Hill wireless station near Bicester and at Grendon Underwood - now an open prison - where she was part of a signals team that worked around the clock to keep contacts open.
"You needed careful listening skills and a quick mind, and some kind of musical ability, because if you tap out Morse it helps to have a rhythm. It took six to nine months to train us to send and receive 25 letters a minute, in groups of five." The first and last groups, she says, gave the key to the code.
She worked in a signal office, with a military policeman and a guard dog outside the door. "On a board were the code names of the agents - Petticoat Red, Lapwing and so on - and what time they would be coming on air. And we had a big book with details of their call sign, and how many messages there were for them. We didn't know where they were, other than that they were in occupied Europe. I thought the Lapwings were probably in Norway, but the others were probably all in France.
"I remember our commanding officer telling us to listen carefully because people's lives were at stake and this thin signal could be like a child crying in the night; and that some of the agents were operating with the set under their bedclothes. I also remember being told about how careful they had to be not to give away their English-ness. One was caught because someone saw him in a chemist's shop picking up a bar of soap and smelling it, which is apparently an English trait."
The work was exciting, but daunting. "We couldn't keep the agents on the air for too long - nine minutes was the limit. But sometimes there would be atmospherics, then they'd ask us to repeat things. I was operational when things went badly in Holland, at Arnhem. It was the only time I found out what the messages said, because we were so busy that I was taken off the wireless sets to stand behind the teleprinter and check the messages. And they were desperate. One said - and I don't know if I should be telling you this, even now - 'five crack Panzer divisions approaching', and another said, 'send us the arms, or pack in your bloody war'.
"I'm glad I didn't know what was in the messages, because you got to know the agents - everyone's got a special touch. And then some names wouldn't come up on the board any more and we'd realise they'd been caught. Although when Paris was liberated there was an agent who must have been there because he was so excited that this flood of uncoded language suddenly came through."
She had no idea what she would be doing when she joined up. The advertisements simply said: "Confidential government work". She says: "I couldn't tell my mother, and no one else had any idea."
At the end of the war, she was due to sail to Port Darwin in Australia to be part of a resistance movement in the Far East. She did not know, but she was one of a group of Fanys scheduled to set up a secret radio station to monitor Japanese activities. To her disappointment a dock strike delayed sailing, "and then the atomic bomb dropped".Soon she was discharged and training to be a teacher because her mother said she had to have a proper career.
Over the following decades she taught in primary schools in Plymouth and became head of Swinley primary school in Ascot, Berkshire, before going to Exeter University to get an education degree, and then teaching at Whitelands College, in west London. In the mid-Sixties she went to work with the British forces' schools in Germany, and in 1971 became a schools inspector for the London borough of Kingston-upon-Thames, where she worked until 1988.
Being a Fany, she says, gave her a sense of discipline and the ability to organise and get on with things. "Neither my mother nor my daughter could understand my loyalty to the Fanys until our 60th anniversary, when we had a lovely service at the Guards Chapel. They came to that; then they said they understood."
Her daughter, Helen Jones, a historian specialising in the role of women, mentions the Fanys in her books whenever she can. "And, you know, I never knew where I was supposed to be going in the Far East until that anniversary service. I was wearing my uniform, and an old Fany officer came in and said, 'My goodness, there's the girl who was going to that little island of Mauritoy (in the Pacific, north of Australia)'. That was the first I knew about it."