I—JUNE 14, 2012

Jacqui met Bob Lambert at an animal-rights protest in 1984, when she was twenty-two. Their son was born the next year. Illustration by Alex Williamson / Clockwise from Top: Keld Navntoft / AFP / Getty; Graham Turner / Keystone / Getty (London Police); William Lovelace / Express / Getty (Margaret Thatcher)

It was four o’clock on a Thursday afternoon, and Jacqui had just got home from work. She made a pot of coffee and took it out to the garden with the Daily Mail. It was the start of her weekend. The sun was out. She sat down at a patio table and poured the coffee, taking a minute to enjoy the scent of the wisteria that was blooming on her trellis.

She opened the paper: the Queen in Nottingham for her Golden Jubilee; bankers under scrutiny; wives and girlfriends of the England football team. Absent-mindedly, she continued to read. She barely glanced at an article titled “How Absence of a Loving Father Can Wreck a Child’s Life.” A few pages later, she came to a photograph of a smiling young man with bouffy brown curls that parted like curtains around his eyes. Even after twenty-five years, she knew the face’s every freckle and line.

She subsequently told a parliamentary committee:

I went into shock. I felt like I couldn’t breathe and I started shaking. I did not even read the story which appeared with the picture. I went inside and phoned my parents. My dad got the paper from their nearest shop and my mum got out the photos of Bob and our son, at the birth and when he was a toddler. They confirmed to me, by comparing photos, it was definitely Bob.

Bob Robinson was Jacqui’s first love and the father of her eldest child. He had disappeared from their lives in 1987, when their son was two. (To protect her son’s privacy, Jacqui asked me not to use her last name.) Over the years, Jacqui had tried many times to track Bob down, but she had never been able to find him. Neither had any of the government agencies she had enlisted to help in the search. Bob had seemingly vaporized. Now there he was, staring back at her from the pages of a tabloid.

Jacqui tried to focus. “An undercover policeman planted a bomb in a department store to prove his commitment to animal rights extremists, an MP claimed yesterday,” the article that the picture accompanied began. “Bob Lambert is accused of leaving an incendiary device in a Debenhams in London—one of three set off in a coordinated attack in 1987.” (No one was hurt in the attacks, which caused millions of dollars’ worth of damage to the stores, targeted because they sold fur products.) It went on to explain that Caroline Lucas, an M.P. for the Green Party, had invoked parliamentary privilege to make the accusation. She was calling for “a far-reaching public inquiry into police infiltrators and informers.” Jacqui read on. The officer, the article said, had insinuated himself into animal-rights groups in the nineteen-eighties, creating an alter ego under which, for several years, he led a double life. Bob Robinson was Bob Lambert, and Bob Lambert was a spy.

II—1984-87

Bob and Jacqui met in early 1984, at an animal-rights protest outside Hackney Town Hall, in East London. Jacqui, who was twenty-two, was wearing a red uniform, with a nametag and a knotted scarf. “Why are you dressed like that?” Bob said, approaching her. She replied that she’d come straight from her job, at Avis Rent-a-Car. Gangly and polite, Bob struck Jacqui as slightly awkward. He was clearly in his thirties—old, to her mind. She found him nice-looking, but didn’t dwell on their encounter. “I didn’t go home and think about him,” she told me recently. “It wasn’t, like, ‘Wow!’ ”

A month or so later, Bob showed up at another demonstration, in the English countryside. A hunt club was holding a fox hunt, which Jacqui and her fellow-“sabs”—saboteurs—were doing their best to disrupt. “They had their little drink before the hunt—it’s got a special name—they were all wearing their gear,” Jacqui recalled recently. As the tweed-jacketed field trotted by, the activists, their faces masked by balaclavas, blew horns (to distract the hounds) and sprayed eucalyptus oil (to dull the scent of the quarry). The skirmishing was a form of class warfare as well as a clash of ideals. “What it really turned into was hunt supporters hunting us,” Jacqui said. “The hunt master, he didn’t care about killing foxes—it was hunting sabs. He would, like, whip us with his whip, and the police would just be standing around watching.”

The protesters finished the day muddy and elated. Bob asked Jacqui if she wanted a ride home. “It was a dirty old Escort van,” Jacqui recalled. “But if you had a van you didn’t have to get the train back to London, and also you could get quite a lot of people in the back.” Bob offered to chauffeur Jacqui’s friends; when they got back to London he dropped the friends off first. Outside her flat, Bob and Jacqui sat in the van and talked. Jacqui recalled, “That happened a couple of times, and, eventually, I invited him in.”

Soon Bob and Jacqui were a couple. The age difference wasn’t an issue. Bob, who said he was an odd-job gardener, seemed no more settled than Jacqui and her peers. Moreover, his tastes and values chimed perfectly with hers. He took her to see the Pretenders at the Hammersmith Odeon and haunted Housman’s, the radical bookstore. Unconcerned about possessions, he rented a tiny bed-sit. His clothes often had a musty smell, as though he had trouble getting them to dry.

As Rob Evans and Paul Lewis write in “Undercover: The True Story of Britain’s Secret Police,” Lambert “was well versed in political theory.” A former acquaintance told them, of Bob, “He was not a cardboard activist, he had real depth to him.” (Evans and Lewis exposed many of the events in this story in a series of articles in the Guardian, for which they won a 2014 British Press Award, and in “Undercover,” which is the definitive account of the excesses of undercover policing in Britain.) He urged Jacqui, a vegetarian, to become a vegan. With his long hair and off-the-grid life style, he seemed the embodiment of the anti-consumerist ethos of the British far left in the Thatcher age.

Politically outspoken as he was, Bob said little about his background. He attributed his reticence to a painful childhood. His mother, he said, had died of cancer when he was young. He had a brother to whom he wasn’t close. From time to time, he would take off in the van to visit his father, who had dementia and was living in a nursing home in the North of England. Whenever Jacqui offered to come along, Bob would say that his father was too far gone for it to be worth the trip. Something about Bob’s solitary, apologetic air brought out her nurturing instincts. “Do you know how Princess Diana used to do that sideways, victimlike look?” she recalled. “He was, in some ways, quite geeky and awkward, and you wanted to sort of care for him, because he had no one.”