The miners’ strike was in its last month. Arthur Scargill was about to join General Galtieri as another defeated leader who had underestimated his lady opponent.

Mrs Thatcher was in the sixth year of her premiership. Friday, February 1st 1985 was the tenth anniversary of her becoming leader of the Conservative Party, and she had agreed to grant an unprecedented real-time one-hour face-to-face interview with an experienced interrogator, Peter Jay of Channel 4’s “A Week In Politics”. No other prime minister, before or since, has dared to do the same: no knowledge of the questions in advance, no respite during the as-live recording, apart from the single designated 3-minute commercial break.

We had spent weeks preparing. She was carving a chunk out of her busy day, en route from Downing Street to Chequers for a working weekend, accompanied just by her press secretary, Bernard Ingham, and her security detail. The Molinare studio on the edge of Soho was abuzz with anticipation. The production team (led by producer Anne Lapping – I was the executive producer) retired to the control room, ready to prompt Peter should the need arise (it didn’t).

Jay – one-time presenter of ITV’s Weekend World, on which both Anne and I had worked, then HM Ambassador to Washington (courtesy of David Owen and his father-in-law James Callaghan), then dislodged leader of the TV-AM breakfast franchise – devoted the first half of the interview to economics.

The economic record of Mrs Thatcher’s government – even allowing for two years of world-wide recession – was spotty, at best: unemployment at a record post-war high, the pound at a record low. As she tried to defend her performance, she suggested that speculators were damaging the exchange rate, and that her interventions had mitigated the damage.

Jay – not just metaphorically – raised his eyebrows: surely the market determined the value of sterling, and governments bucked the market at their peril? She retreated, a little. But then the questioning turned to monetarism and Milton Friedman. In the gallery, we watched open-mouthed as Mrs Thatcher denied being a follower of Friedman, or a monetarist – “a theory to which I have never subscribed”. So do you not believe that there is such a thing as the natural rate of unemployment – the equilibrium level? “No, but you cannot spend your way out of unemployment.” So you do accept there is a natural rate of unemployment?

By now, Jay was doing his best to avoid eye contact with Mrs Thatcher, as she visibly glowered under his questioning. She changed tack. “I tend to look at you as a great expert. You are asking me the questions, and you know the answers.” But then she ventured that European countries were disadvantaged by the fear that socialism would be imposed – a fear to which America was immune, giving it an advantage in the markets for borrowing. “Are you saying that after all your years in office the markets are haunted by the fear that Neil Kinnock will replace you?” “I reject the philosophy that for every problem there is a subsidy.”

But don’t governments support job creation? Yes, but these are real jobs – productive jobs – which we want to encourage – not phoney jobs. And what do you produce? Or is your job as prime minister also a “phoney job”?

At last the break. Despite the palpable tension in the studio, Mrs Thatcher patiently and charmingly posed for photos with the studio crew.

Part two was much more about Mrs Thatcher’s political beliefs. What do you mean by “one of us” and “the enemy within”? How do you feel about Harold Macmillan dismissing you as an 1860s Manchester Liberal? Were you disloyal to Ted Heath? If you disagreed with his policies, why not speak out more when you were in his cabinet? Do you believe that inequalities flow from differences in talents?

This was more her favoured ground. She re-iterated her belief in de-regulation, privatisation, lower taxes, hard work, personal responsibility, self-discipline, endeavour and the voluntary spirit – whilst supporting the NHS and education. No mistaking the Grantham grocer’s daughter in this vein.

Finally, a direct question on the strike: shouldn’t you try to unify the nation by offering the miners’ union talks? “Never compromise with the anti-democrats, with violence, with intimidation.”

The production team repaired to the hospitality room, mentally exhausted. Mrs Thatcher bustled in, in high spirits, gently chiding Jay over his monetarism questions: “dear, your viewers won’t be interested in any of that!”

She demanded a whiskey from Bernard Ingham, and buttonholed Jeremy Isaacs, Channel 4’s chief executive. She was full of enthusiasm for a young entrepreneur she had been visiting, who manufactured yoghurt. Another whiskey, and then at last Ingham urged her that it was time to set off for Chequers. As she departed, it felt as if a force field had left with her. I realised I had a severe migraine.

(You can read the full 10,000 word interview on the Thatcher archive at www.margaretthatcher.org/document/105955)