Margaret Thatcher’s infamous “No, no, no” retort to Jacques Delors, a historic moment in the UK’s relationship with Europe, which also had the effect of precipitating her downfall, was partly inspired by an article penned by a young journalist named Boris Johnson, her newly released private papers show.

In 1990, 30 years before Johnson took the UK out of the European Union, an article he penned as the Telegraph’s EC (European Community) correspondent warning of the threat the EC posed to national sovereignty was in Thatcher’s briefing pack as she delivered the combative speech to parliament.

Johnson’s article was accompanied by a covering note from the Foreign Office in which Thatcher had underlined the words: “Federation of Europe”.

The prime minister’s address on 30 October 1990, pushing back against Delors, then European commission president, came as the government was hugely unpopular and Thatcher was trying to balance divisions over Europe within the party. Seen as a way for her to reassert her authority, it provided succour for Eurosceptics within the party and the press but was too much for some Conservatives.

Two days later the Sun ran its famous “Up Yours Delors” front page but, on the same day, the deputy prime minister, Geoffrey Howe, resigned, criticising Thatcher’s stance towards Europe. It was the beginning of the end for the prime minister, who would make her tearful exit from No 10 by the end of the month.

Chris Collins, a historian at the Margaret Thatcher Foundation, described the presence of the article by Johnson as “poignant given what’s happened since”.

He added: “It’s part of the trigger. Clearly, it’s there … to remind her to have a bash at Delors, which is good politics in this context but also I guess to remind her of the mood that is surrounding this issue. I mean, a lot of Conservatives would read articles like that one by Boris Johnson … and say yes, that’s what these guys [like Delors] are up to.”

Johnson has often sought to channel the legacy of Thatcher during his political career, not least on Europe, despite her position on the issue having been more complex than often presented by Eurosceptics.

During his time as the Telegraph’s EC correspondent, he was a prolific peddler of Euromyths, including plans to ban prawn cocktail crisps and for a “banana police force” to regulate the shape of bananas, often with little foundation in fact.

And despite the fact that Johnson’s article – headlined “British right of veto faces axe in Delors plan” – was included in Thatcher’s folder for her all-important speech, the Foreign Office, in its covering note, made the observation that it was actually wrong.

Her private secretary, Richard Gozney, wrote that the commission’s opinion “does not contain what M Delors is reported by the Daily Telegraph as having suggested. It does not propose any radical change in the present institutional plans of the community – although it does contain a lot of horrors.”

Thatcher was clearly aware of this as she highlighted the word “not” in yellow highlighter. But Collins said Delors’s comments were only ever a straw man for her team.

“They know there isn’t going to be an instant federation of Europe and that the French president doesn’t want to be subordinate to the European commission. So, you know, in a way that’s an easy one. And you just hammer that one and she does a marvellous performance and so on.”

Howe begged to differ, delivering a devastating critique of her in his resignation speech on 13 November, paving the way for a leadership challenge by Michael Heseltine. After Thatcher fell short of the votes required to avoid a second round she announced her departure on 23 November, leaving Downing Street five days later.

The papers, the last to be released of Thatcher’s premiership, provide little insight into her feelings towards those she undoubtedly blamed for bringing her down.

However, Collins said the stock replies sent in her final days as prime minister to some well-wishers – compared with the highly personalised letters sent to others – “were probably meant to sting”.

A letter from the then education secretary, Kenneth Clarke, one of those who advised her to resign after the first leadership ballot, was florid in its praise of “a truly great prime minister” and said he only acted to save her from “humiliating defeat” in the second round. Thatcher appears to have given it short shrift, with “stock” written across the top.

By contrast, in the final letter she wrote as prime minister, published for the first time, she paid tribute to her long-serving chief press secretary, Bernard Ingham, “from the bottom of my heart, for 11 years of loyal and trusty service and companionship”. She continued: “It is with great admiration and heartfelt thanks that Denis and I say goodbye to you and to No 10 – for the two are almost inseparable in our minds.”

Collins said it illustrated “such a contrast between her very difficult relationship with colleagues and her very warm, almost loving relationships with many long-lasting staff”.