As a small addendum to the coverage of Margaret Thatcher's death, announced today, there is an intriguing insight into her early history as Tory leader and the vexed issue of Scottish devolution from a fresh batch of US cables published by Wikileaks.

Then into her second year as Tory leader, that one issue appeared to exemplify her ideological rigidity and move to the right for US diplomats in London. They use the words "rigid", "English backlash" and "narrowing its base".

Wikileaks has posted online a vast tranche of 1.7m originally secret and confidential US cables, which Wikileaks has culled from declassified papers held by the US National Archives; buried within it are a series of cables about the fraught and immensely divisive debate about Scottish (and Welsh) devolution at Westminster.

The so-called Public Library of US Diplomacy documents (search here: https://search.wikileaks.org/plusd/, keyword: Scotland) throw up a series of intriguing insights into the warfare within the then Tory party, where Thatcher was publicly insisting she endorsed her party's official support for devolution, while appearing to do all she could to thwart Labour prime minister Jim Callaghan's efforts to introduce it.

Belying the notion that the Tories were uniformly implacable opponents of devolution, the cables record her predecessor and former prime minister Ted Heath's enthusiastic support for decentralising power from London to Edinburgh; several prominent Scottish Tories, including Alick Buchanan-Smith, then a shadow Scottish secretary and his then deputy Malcolm Rifkind, resigned in protest at Thatcher's intransigence.

Others tried to – Hector Munro, a future Scottish Office minister, George Younger, a future Scottish Secretary, and Russell Fairgrieve, then Scottish party chair - but were rebuffed. One document notes the dispute had "torn... the fragile fabric of Tory party unity."

The then confidential US embassy London cable, titled The Tories and Devolution, which discloses US diplomats were gleaning confidential information from Tory MPs on the issue (a potentially acute one given the US's then significant defence interests in Scotland) dated 10 December 1976 states:

The present difficulty also confirms criticisms of Mrs Thatcher's leadership which were made at the time of her latest shadow cabinet reshuffle, that she was moving the party perceptibly to the right and narrowing the base of the party's appeal. This criticism has been levied both by the head of the Tory Reform Group in a public comment December 7 and earlier in a Conservative MP's comment to an embassy officer. The Tories now appear to be the voice of the English backlash on devolution, increasingly rigid in opposing devolution.

Another previously secret State Department memo to the CIA, Department of Defense, the White House and Joint Chiefs of Staff, dated 13 December 1976, headed Morning summary of significant reports, baldly stated this:

Embassy London comments that the Tories now appear to represent the voice of English backlash against devolution, and that Mrs. Thatcher has become more susceptible to criticism that she is moving the party to the right and narrowing its base.

That memo also made this observation:

The Tory leadership's ambivalent signals concerning the Scottish devolution bill have caused internal disunity and weakened the party's efforts to obtain support in Scotland.

In the event, Callaghan prevailed; then at least. He forced his devolution bill through, will ill-defined promises of referendums in Wales and Scotland; Thatcher imposed a three whip on her party to oppose it. Both saw small rebellions and abstentions – Heath and four other Tory MPs voted with Callaghan in favour.

On 17 December 1976, a cable from the US embassy in London for the State department, headed Devolution: government majority of 45, noted: