Having had a ringside seat during her rise to power, Jonathan Aitken is a biographer who saw many sides to Margaret Thatcher. Gill Oliver talks to him about his rollercoaster journey

From time to time biographer Jonathan Aitken caught the rough side of Maggie Thatcher’s tongue. But then so did most people, he says. The former Tory MP and minister had a ringside seat while she was leader of the opposition and after she became Britain’s first female Prime Minister.

In his 700-page tome, Margaret Thatcher: Power and Personality, he details her insecurities, prejudices, courage, intelligence and abrasive management style that would lead to her downfall.

The Old Etonian and Oxford University graduate was in an ideal position to witness this at first hand, since he dated Mrs Thatcher’s daughter Carol for three years and even after they parted remained a trusted family friend.

He analyses the key moments in her life and career, including her successful bid to replace Ted Heath as Tory leader, her often acrimonious relationships with her cabinet ministers, the triumph of the Falklands War, the miners’ strike and the poll tax riots.

He tells of how she returned to the Thatcher family home late one night after a particularly bruising day and they drank The Famous Grouse while she tearfully poured her troubles out to him. He pointed out: “There were many different sides to her. “Margaret put up this carapace of iron to the world but in some areas she was an old softie.

“She could be absolutely charming but there were other times when I couldn’t believe how awful she was.”

Jonathan Aitken was never invited to join Thatcher’s cabinet and commentators have suggested that breaking off his tryst with Carol led to political exile by her mother but there was never any formal engagement and he does not believe that was the true reason.

He said: “It was a bad career move being Carol Thatcher’s boyfriend but I have nothing but good things to say about Carol and nothing except nice things to say on a personal basis about Margaret.

“The idea that Margaret Thatcher exiled me for years really isn’t true, although I am sure like any mother she had feelings about it. “Actually Margaret Thatcher and I got on pretty well.”

Rather, he believes his strong Euro-sceptic stance was the thing that did for him.

This is his 14th book, a natural progression given that while he was at Oxford, he wrote for university publications Isis and Cherwell and went to work as a journalist at the London Evening Standard and Yorkshire TV, before going into politics.

One of his best-known other subjects was disgraced former-US president Richard Nixon.

Nixon: A Life, which was published in 1993, was unauthorised but unlike many others who wrote about the man, he had many face-to-face and phone interviews with Nixon. He pointed out: “He was a complex character and had all kinds of insecurities, which at certain times could give him an Achilles heel and interestingly, both these things are true of Margaret Thatcher. Margaret Thatcher had a much stricter moral code than Richard Nixon but Nixon’s achievements, such as detente with Russia and getting America out of the Vietnam war, were on a grander scale than anything Margaret Thatcher could do. “But both were very much more human than they appeared.”

The 72-year-old admits he could be reckless when younger, admitting: “I took too many risks for my own good.”

He recalls a long lunch with his great uncle, Lord Beaverbrook, when he was 19, during which the newspaper magnate told him ‘Jonathan, you are a bright boy but I hope you don’t turn into a dull man like that father of yours. My advice to you is stir up the mischief, stir up the mischief.’”

And there’s no denying, the father-of-four has done that.

In 1999, he was sentenced to 18 months for perjury during a libel case and sent to Belmarsh Prison, where he served seven months alongside convicted murderers and gangsters. He describes the experience as “Defeat, disgrace, divorce and bankruptcy – it was horrendous. “But the actual prison bit was more positive than I would have believed possible and I got along with my fellow prisoners rather well.

“I found I had a trade writing and reading letters for those who couldn’t and I enjoyed the camaraderie and humour.”

He’d been inside for barely a week, when a vicious knife fight between two prisoners broke out, causing large numbers of prison officers to rush onto the wing.

“They pinned us all against the wall and interrogated us about what had happened,” he recalled. “In true schoolboy fashion, I said I hadn’t seen anything. “Alongside me, an old lag from gangland London said: “Just like Jonno, I never saw nothing, neither’.

“As we walked away afterwards, he said ‘We’re the only people left these days who don’t grass – the old lags and the Old Etonians.’”

Aitken’s experience in prison proved a spiritual journey, after he converted to Christianity. After his release, he returned to Oxford to read theology at Wycliffe Hall and has been president of the Christian Solidarity Worldwide for seven years. Despite his very public disgrace, Maggie Thatcher and family did not turn their backs on him.

“When I came out of prison, Carol was a wonderful friend and Mark went out of his way to say things like ‘Can I lend you an office? Do you need cash?’” he said.

“I remember the phone rang and a voice said ‘Dennis here, would you do me the honour of joining me for lunch?’ “At first, I thought it was Rory Bremner but it really was Dennis.

“Margaret was very good, too.”

Around the same time he also found himself splashed all over the front pages of the tabloids after it was revealed he’d fathered a love child, following a secret affair with socialite Soraya Khashoggi.

With the paperback version of his Thatcher biography out this month, he is doing endless interviews and answering personal questions about times you’d think he’d prefer to forget.

But actually, he seems extremely at ease with his turbulent past, pointing out: “Most people’s lives are roller-coaster rides. “Mine happened to be a roller-coaster ride in public but sooner or later, all of us hit the dips.”

Visit oxfordliteraryfestival.org for more details

Jonathan Aitken will talk about Margaret Thatcher: Power and Personality on Sunday, March 23 at 12pm. Tickets £11-25.