On 4 May 1979 James Callaghan left Downing Street, making way for Margaret Thatcher. But, that very day, he made sure that she would receive key documents covering his secret efforts to secure a replacement for Britain's nuclear deterrent.
This was breaking the "Iron Law" of Whitehall, according to Peter Hennessy, Professor of Contemporary History at Queen Mary University of London. Incoming governments never see the files of the outgoing administration: instead, they are given a more neutral briefing by civil servants.
The files show that in March 1979 Callaghan was already preparing to pass some notes on if he lost the election. He had been concerned for some time that Britain's Polaris missiles were becoming outdated, and that to retain a credible deterrent Britain would need a more sophisticated multiple warhead system.
At Guadeloupe, in January 1979, he had discussed this with the US president Jimmy Carter, in private talks with no officials present. Carter agreed that Britain could have the most modern technology: Trident.
Callaghan had met US President Jimmy Carter in Guadeloupe in January 1979
All this had to be top secret. It was longstanding Labour Party policy that the deterrent would not be replaced. At a time of economic crisis, such an investment would be deeply unpopular.
Nonetheless, James Callaghan felt so strongly about the issue that he wrote to Jimmy Carter to check that he could put their conversation on the record, and Mrs Thatcher could know what they'd discussed.
The president agreed. Then,
in a handwritten note
, dated 4 May, Callaghan clarified that he didn't want Mrs Thatcher to receive his personal letter to President Carter or the meeting notes, but that she should be briefed "on the replacement of Polaris or otherwise - as she thinks!".
Professor Peter Hennessy interviewed James Callaghan before he died - he made clear that "briefing" meant she should receive detailed technical reports he'd commissioned.
Jim Callaghan admitted he had broken with precedent in this case. Professor Hennessy describes Mr Callaghan as an "old patriot" who put national interest - as he saw it - before Whitehall rules.
"Extremely firm line"
Margaret Thatcher also saw the Polaris replacement as crucial. The newly-released files show that one of the first things she did was to set up a special cabinet committee on the subject.
And while she saw the Soviet Union as a real threat, she was not intimidated by Soviet leaders. She had her first meeting with a senior Soviet figure the Prime Minister Alexei Kosygin, in June 1979.
The file records that he told her the Soviet Union was a peace loving country which did not produce all the massive armaments which the prime minister attributed to them. "the prime minister told Mr Kosygin that he should not be so modest" runs the note in another newly released file: "nobody who had seen the Soviet tanks and missiles which were paraded through Red Square would underestimate the Soviet Union's capacity".
Margaret Thatcher entered Number 10 on 4 May 1979
Sir Bryan Cartledge took that note. He was then Mrs Thatcher's private secretary. He remembered that Mr Kosygin was "quite nervous" and oddly "courtly" in his behaviour.
He told me "At the end he said he hoped she hadn't been offended by the way he'd introduced some of the topics they'd been talking about - which for a Soviet leader was quite extraordinary really!"
The files show Mrs Thatcher's determination to cut public spending. She put pressure on her ministers, arguing with the chancellor.
One area she wanted cut was the civil service. Advised that only 3% staff reduction could initially be achieved she scribbled "no" - underlined it - and "too small" in the margins, in blue ink.
She lost this particular battle though - as she'd had to admit defeat in her similar argument with her chancellor Geoffrey Howe.
She wanted him to cut government spending more dramatically in his first emergency budget:"We have now taken an extremely firm line on public spending and I do not think that there are more economies of any significance to be found" he wrote. She "reluctantly agreed" to Howe's main proposals.
And as well as the National Archives, the
Margaret Thatcher Foundation
is also set to release hundreds of documents relating to her first months in power.
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