Newly released papers reveal how PM’s press secretary flouted neutrality rules by giving advice on Tory campaign strategy.

Margaret Thatcher’s press secretary advised the then prime minister that her first media priority for the 1987 general election campaign was to “look after the Daily Mail”, the latest release of her private papers show.

The set of files from the Margaret Thatcher Foundation reveal that Sir Bernard Ingham, nominally a civil servant rather than a Conservative party employee, gave her advice despite neutrality rules that banned him from doing so.

In a note to the prime minister on “how to play the media over the next couple of weeks” before the campaign, he wrote: “You need to look after the Daily Mail(David English wants to interview you – and would like to be first to do so after you have declared an election).” English was the paper’s editor at the time.

Ingham also offered a view of two rivals to the Mail. “The Daily Telegraph is to interview all the party leaders and publish their Q and A during the course of the campaign,” he said. “George Jones and Simon Heffer have specifically asked to come and interview you. Whatever your views about Max Hastings you should not pass this up.” Jones and Heffer were members of the Telegraph’s political staff, while Hastings was the newspaper’s editor for 10 years.

The only other paper to feature in his plans is the Sun, which wanted her to answer readers’ questions, he told her: “They recently did a similar interview with [Neil] Kinnock who came out of it very badly. They will treat you very well and you should do this.”

The files also show that Thatcher’s most trusted adviser, her political secretary, Charles Powell, also a civil servant, told her the day after she won a historic third term in June 1987 not “to put yourself through it again”.

“The level of personal abuse thrown at you during the campaign was unbelievable and must take some toll, however stoic you are outwardly,” Powell wrote on Downing Street-headed paper in a “strictly personal” note. He added: “It is not right you should be subjected to a further round like this time.”

Powell, speaking this week about the release of his 1987 letter for the first time in full, admitted it was an unusual one for a civil servant to send but said he had been distressed to observe at close quarters the stress of a third election campaign “and the backbiting it involved on Margaret Thatcher’s health and performance and wanted to discourage her, in her own interests, from any inclination to go ‘on and on’.”

He recalled discussing the letter with Thatcher, who had felt there was “as yet no suitable successor to her, though several thought they were”.

Thatcher faced what she regarded as a bruising time from broadcasters, particularly Sir Robin Day and David Dimbleby, who both focused on her “uncaring” reputation, as she privately told the journalist Sir John Junor: “All the interviews I had seemed to me to be more belligerent, more discourteous, more insulting than any I ever remember – and I have been through a lot.”

But her private papers, held at Churchill College in Cambridge, also show how vulnerable Thatcher became during the campaign after losing the services of her two most trusted advisers, Powell and Ingham – owing to civil service impartiality rules – even if they continued to give her advice.

They also underline how far she had to rely on the Conservative central office party machine that was so riven by fractious disputes between the party chairman at the time, Norman Tebbit, whom she no longer trusted, and her placeman, Lord Young. Tebbit’s then chief of staff, Michael Dobbs, has said the situation inspired him to write his political thriller House of Cards.

Thatcher biographer Charles Moore reveals that she repeatedly lashed out and exploded in anger during the campaign, even at one point, according to Dobbs, “screaming and foaming at the mouth”.

On “wobbly Thursday” – 4 June 1987, when the Tories were spooked by a poll showing Labour closing the gap one week before the election – Moore even reports that Young grabbed Tebbit by the shoulders and said: “Norman listen to me, we’re about to lose this fucking election, you’re going to go, I’m going to go, the whole thing is going to go.”

The files contain one unsigned note from “‘wobbly Thursday”, which traced a general slide in the Conservatives’ polling position over the whole campaign and reported that “the trend is now dangerous”.

The private papers confirm that the main dispute between Tebbit and Young was how to play the campaign. Young, backed by ad agency research, wanted an all-out attack on Labour’s “extremism”, while Tebbit argued that the Tories had to give voters a positive reason to keep the party in power.

The wobble was brought to an end by a Guardian/Marplan poll showing a 10-point lead which Tebbit gleefully reported to Thatcher: “I believe this confirms our positive strategy is right. I believe the negative material which we asked Saatchi’s to produce is not the best line. We need less about what life would be like under Labour and more about life under this government.”

As well as the note on managing the media, the files include two notes, entitled Election Analysis, written during the course of the campaign which are unsigned but bear Ingham’s unmistakeable tone – “we should be having all the fun of the Eatanswill fair”, one reads.

The author notes that the aim of the Tory campaign “should be to destroy Labour’s claim to be the caring party which its ‘Chariots of Fire’ commercials are designed to achieve”. Kinnock’s campaign had featured a party election broadcast directed by Hugh Hudson, the director of Chariots of Fire. The highly personalised broadcast was dubbed “Kinnock: The Movie”.

In the event Labour’s campaign was to prove a “magnificent defeat”, and Thatcher overcame her party’s fractious campaign to win a historic third term with a reduced majority of 102.