Smash hit

For Quinn, a gregarious, emotional socialite, the timing of the story was tricky. Pregnant with her second child, she had been trying to end her affair with Blunkett for some time and pursue a more settled family life, a source said last week. She felt intimidated by Blunkett’s “relentless ardour”.

To get a better understanding of the messy ending of the affair one has to know how it began.

Quinn had long harboured a burning desire for children. Some years earlier, during her first marriage to Michael Fortier, she had bought a designer dog as a sort of baby substitute. Lady Felicity Davis, the breeder from whom Quinn acquired the Dandy Dinmont terrier, recalled: “She suddenly burst into tears. She said that she desperately wanted a baby but her husband wouldn’t let her.

“She hoped if she got the puppy and looked after it responsibly, she could persuade her husband to have a child.”

Quinn pampered the dog and even took him to her office, but her dreams of a baby remained unfulfilled. She began an affair with Stephen Quinn, a 60-year-old publisher at the magazine company Condé Nast, who became her second husband in 2001. He is, according to one friend “a charming, beautiful, gorgeous Irishman”.

Just after they married, however, Kimberly appeared on the Radio 4 programme Poetry Please, of which Blunkett is an avid fan. Blind from birth, Blunkett’s world is dominated by sound. He was captivated by her voice on the radio.

Blunkett’s biographer Stephen Pollard has revealed that when, soon afterwards, in the summer of 2001, The Spectator asked to interview Blunkett, he agreed.

“He consented to the request, provided he could have dinner afterwards with Boris Johnson (the magazine’s editor), interviewer Petronella Wyatt and the alluring Ms Fortier,” said Pollard.

The two hit it off immediately, the glamorous American turning on her full range of flirtatious charm. At the end of the evening Blunkett gave her his private phone number. Within months she was pregnant with William, whom Blunkett last week described as “my son”.

Stephen Quinn was unaware of the affair, apparently thinking that the blind Blunkett was far too busy to be a threat to his new marriage.

Life at his home in Mayfair seemed entirely normal, according to their nanny Leoncia Casalme. “It was Stephen who was most hands-on (with William). Kimberly often wouldn’t be home until 9pm or 10pm. He was the one I would see playing with William after work, or singing him lullabies.”

Behind the scenes, however, illicit love was in full swing. In the first six months of the affair, the lovers took two holidays together, in Spain and Italy. Quinn told her husband she was going away with William to have time to bond with him. Stephen Quinn says he had no idea that Blunkett accompanied them.

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