The Scottish devolution referendum held on 1 March 1979 produced a paradoxical result. A majority of those who voted supported the creation of a Scottish assembly, but the proposal was thwarted by a controversial rule included in the Scotland Act 1978.

The outcome triggered a series of events that led directly to the fall of the Labour government and the election of Margaret Thatcher.

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The Scotland Act, which set out the scheme for a devolved Scottish legislature, represented the Labour government’s attempt to respond to growing demands for Scottish self-government.

In 1967, the pro-independence Scottish National Party (SNP) secured a famous victory in the Hamilton by-election.

The SNP’s breakthrough in Hamilton – considered alongside Plaid Cymru’s success in Carmarthen – led to the establishment of the Royal Commission on the Constitution (the Kilbrandon Commission) by the Labour government in 1969. The commission’s work constituted the first major study of the constitutional challenges posed by multi-national governance and rising national consciousness.

The report, published in October 1973 after a four-year inquiry, rejected both independence and federalism for the constituent nations of the UK, instead recommending legislative devolution for Scotland and Wales in the form of elected assemblies.

In September 1974, Harold Wilson’s government published a white paper entitled Democracy and Devolution: Proposals for Scotland and Wales, putting forward proposals based on the Kilbrandon commission.

On 13 December 1976, James Callaghan, who succeeded Wilson as prime minister, introduced the Scotland and Wales Bill (before the legislation was split in two) at second reading. Callaghan argued that devolution was a necessary response to the “movement of popular will”.

This legislation also coincided with a marked shift in parliamentary arithmetic. With the loss of its commons majority, Labour once again relied on smaller parties – like the Liberals and SNP – to prop up the government.

The Callaghan government mostly embraced devolution, but the Labour Party at large was divided. In Scotland, Tam Dalyell served as de facto leader of Labour’s anti-devolutionist tendency. He famously posed the “West Lothian question” (so-called after his constituency), which referred to the perceived imbalance between the voting rights in the House of Commons of MPs from Scottish and Welsh constituencies that would arise with devolution.

Under devolution, Dalyell declared, MPs from Scotland and Wales could vote on issues affecting only England, while English MPs could not vote on matters devolved to Scotland or Wales.

The Scotland Act, alongside the Wales Act, received royal assent on 31 July 1978. Both pieces of legislation included a requirement for post-legislative referenda.

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In Scotland, the question put was as follows: “Do you want the provisions of the Scotland Act 1978 to be put into effect?”

A narrow majority of 51.6% (1,230,937 votes) voted in favour of the act, with 48.4% (1,153,502) voting against.

However, the legislation was subject to an amendment, inserted by the anti-devolutionist Labour MP George Cunningham (a Scot who represented an English seat), which required at least 40% of the total registered electorate to vote ‘Yes’ for the Act to be implemented. The amendment was strongly opposed by the government, but it was passed by 166 votes to 151.

The amendment provided for a double test: a majority in favour of an assembly, and a substantial turnout.

On a turnout of 63.7%, the ‘Yes’ vote represented only 32.9% of the electorate, falling well short of the required threshold. Under the terms of Cunningham’s amendment, the Scotland Act 1978 was later repealed by a statutory instrument.

The campaign exposed deep divisions within Scotland’s main political parties. The Labour Party was officially in favour but was damaged by a highly effective Labour Vote No campaign, of which Brian Wilson served as chairman, and Robin Cook and Tam Dalyell as vice-chairs.

The Conservative Party also campaigned for a ‘No’ vote. Malcolm Rifkind, a future foreign secretary, was among the members of the minority Conservative Yes campaign.

The failure to deliver a devolved assembly, despite a numerical victory for the ‘Yes’ campaign, was seen by pro-home rule campaigners as a democratic betrayal.

Conservative leader Margaret Thatcher then tabled a motion of no confidence in the Callaghan government, which the SNP and Liberals supported. Thatcher’s motion was passed by 311 votes to 310, marking the first time a government had been brought down on a confidence vote since 1924.

At the 1979 general election, the Conservatives won 339 seats (up 62), securing a comfortable working majority of 43. Callaghan’s Labour Party slumped to 269 seats (down 50). The swing of 5.2 points from Labour to the Conservatives was the largest since 1945.

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On the first anniversary of the failed referendum, the Campaign for a Scottish Assembly (CSA) was formed. The stated objective of the CSA, formed of mainly SNP, Labour and Liberal activists, was the “creation of a directly elected legislative assembly or parliament for Scotland with such powers as may be desired by the people of Scotland”.

The CSA was the primary catalyst behind the creation of the Scottish Constitutional Convention (SCC), which formed in 1989 to agree a devolution scheme.

Thatcher’s perceived misrule helped craft a pro-devolution consensus in Scotland.

In 1995, the SCC produced a blueprint for a Scottish parliament, Scotland’s Parliament, Scotland’s Right, which formed the basis of New Labour’s proposals.