The Special Operations Executive (SOE) used women as agents because they would not stand out compared with young men, who should have been in military service or war work. Although it might cause gossip, in wartime women were able to meet people, invite them home and even stay the night with them. Women were recruited mainly on their ability to speak French, blend in, keep a cool head and think quickly.

This mix of bravery and ordinariness characterised many women in spying roles. Marie Madeleine Fourcade was a single mother aged 30 when she started work in resistance intelligence-gathering. She was arrested and escaped twice, and had to send her children aged 10 and 12, alone across the Swiss border to safety.

Her commander wanted to discourage her from returning to France: 'You've gone on long past the safety limits. According to the law of averages, an underground leader can't last more than six months. You've lasted over two and a half years. It's sheer witchcraft.'

Marie Louise Dissard was 60 when she joined the resistance. She became the leader of an escape route with stations in Paris, Marseilles and Perpignan, helping 250 airmen out, 110 of them while she herself was in hiding. Before that, she travelled through France, looking like any other elderly woman, arranging lodgings, accompanying escapees and setting up contacts.

This courage and resourcefulness failed to find an echo in the culture of the British secret services. When Stella Rimington, who was to become the first woman to head a security service, joined MI5 she says: 'It did not matter that I had a degree, that I had already worked for several years in the public service, at a higher grade than it was offering, or that I was 34 years old. The policy was that men were recruited as what were called "officers" and women had their own career structure, a second-class career, as "assistant officers". They did all sorts of support work, but not the sharp-end intelligence-gathering operations. What the recruiters were offering me … was a post as "junior assistant officer".'