A woman named as Gail Foliard, wearing a black wig over her blonde hair, seen on hotel CCTV at the time of the killing

From the moment Mahmoud al-Mabhouh checked into his suite at the Al-Bustan Rotana hotel, he became Gail Folliard’s target. Mabhouh was in Dubai to buy missiles from Iran which would then be smuggled to Gaza and launched on Israel. Gail Folliard was on business, too. The hotel’s security cameras silently observed her as she walked through the ballroom-sized lobby, around the pool area and past the eight restaurants. Ms Folliard paid for her room in cash. It was the first step in ensuring she left no trail.

The passport in Ms Folliard’s shoulder bag was an Irish one, giving her age as 26. We now know that passport was a fake – and that her lipsticked smile (right) concealed that she was a member of kidon, the department of Mossad responsible for assassination and kidnapping. She is one of six women in the unit of 48.

Meir Amit, the director-general of Mossad in the 1960s, laid down the rules for kidon women in a document that remains in force today. It contains the following passage: “A woman has skills a man simply does not have. She knows how to listen. Pillow talk is not a problem for her. The history of modern intelligence is filled with accounts of women who have used their sex for the good of their country… It is not just sleeping with someone if required. It is to lead a man to believe you will do so in return for what he has to tell you.”

These skills are honed during the two-year course all Mossad recruits undergo at the training school, a dun-coloured building outside Tel Aviv. The women are taught how to shadow a target; how to create a dead-letter box; how to break into a hotel room. “Gail Folliard” would have been shown how to pack a gun inside her knickers; stealing passports and disguise are also on the curriculum.

The failure rate is high. Those who pass work either at Mossad’s headquarters in Tel Aviv or at one of its many overseas stations. A few are then considered for further training as kidon. The unit is based in the Negev desert, the pay £2,000 a month. Ms Folliard would have been told that joining the kidon was like joining a family and she would be protected and nurtured. In return she would serve the family in any way it asked.

Arguably the most famous female kidon was Cheryl Ben-Tov, code-named Cindy. Born in Orlando, Florida, Cheryl moved to Israel to study Hebrew and Jewish history. At 18 she fell in love with an Israeli who worked for the Internal Security Service, Shin Beth.

A year after they married, Cheryl volunteered to join Mossad. Her motivation, she later told me, was “the thrill of its mystery”.

Her training taught her, among other skills, how to construct a waterproof strip of microfilm that could be left buried in the side of a river bank. She also learnt how to change her facial appearance by inserting cotton wadding in her cheeks. She became adept at posing as a drunk and chatting up men in nightclubs, then disengaging herself outside their hotel.

With an IQ of 140, and her ideal psychological profile, Cheryl was invited to join the kidon. On the day she was trucked out to its base in the Negev, she was questioned about her sexual experience. Would she sleep with a stranger if her mission demanded it? She answered truthfully: there had been no one before her husband, but if she was convinced the success of the mission depended on it, then she would. “It would purely be sex, not love,” she explained to me.

In 2004, Cheryl joined a team of nine katsas – field intelligence officers – in London. Their task was to entrap Mordechai Vanunu, who had worked at Israeli’s top-secret nuclear facility in the Negev desert, but had fled to London to try to sell his story. Mossad had to stop him from doing so, and Cheryl was chosen as the bait to trap him.

Using her seduction skills, she “came alongside” Vanunu in Leicester Square. Their relationship quickly developed, and Vanunu suggested they spend the night together. Cheryl agreed, saying they should go to

Rome and “enjoy a few romantic days in the city of love”, as she put it to me.

Five members of the Mossad team were passengers on the flight Cheryl and Vanunu took to Rome. In the old quarter of the city, Cheryl led the way up to an apartment she had told Vanunu belonged to her sister. Already waiting inside were the Mossad katsas from the flight. They overpowered Vanunu, injecting him with a paralysing drug. Three days later he had been tranferred to Haifa in Israel. A swift trial and a life sentence in solitary confinement followed. Cheryl Ben-Tov disappeared back into her secret world.

She resigned from Mossad after the Vanunu case. It had “burned” her as an agent, she told me. Today she lives back in Orlando, with her husband and two daughters, running a real estate business.

Tzipi Livni, the head of the opposition Kadima Party in Israel, was another Mossad high-flier. She was posted to Paris as a kidon, carrying out ruthless operations against Arab terrorists. Ephraim Halevy, a former chief of Mossad, has described her as “running substantial risks to get her targets”. She resigned to launch her political career.

Nineteen hours after arriving in the Gulf state, Gail Folliard had left Dubai. In the debriefing in a safe house in Tel Aviv, a Mossad psychologist would have been present. How well did she think her disguise had worked? Had there been any moments when she thought she would abandon her mission?

Gail Folliard, now the subject of an international arrest warrant for murder, will vanish. She may undergo surgery to change her appearance. Her passport will be burned. No one – not her husband nor boyfriend nor family – will be allowed to contact her for months. It should be sufficient for them to know that she was a heroine to Mossad.

‘Gideon’s Spies: The Inside Story of Israel’s Legendary Secret Service’ by Gordon Thomas is available from Telegraph Books at £14.99 plus £1.25 p&p. Call 0844 871 1516 or visit books.telegraph.co.uk