REVOLUTION was in the air during May 1968. From Beijing to Belfast and Paris to Prague, student protests shook the establishment. Even in Edinburgh the city's university had recently ousted Malcolm Muggeridge as rector, while the usually sleepy town of Perth witnessed a revolution of its own, albeit of a peculiarly British sort.
The unlikely setting was the annual conference of the Scottish Conservative and Unionist Association and the equally unlikely revolutionary was Edward Heath, Leader of the Opposition since 1965. As he rose to make his speech on the afternoon of Saturday, 18 May, the party faithful had no reason to suspect anything beyond the usual Unionist rhetoric about the evils of socialism.
Instead, Heath dropped a bombshell. "I propose that … a Constitutional Committee should be set up to examine proposals for the reorganisation of Scottish Government," he declared. He continued, "We would propose to the Constitutional Committee the creation of an elected Scottish Assembly, to sit in Scotland.
"Let there be no doubt about this: the Conservative Party is determined to effect a real improvement in the machinery of government in Scotland. And it is pledged to give the people of Scotland genuine participation in the making of decisions that affect them – all within the historic unity of the United Kingdom." Heath's speech quickly became known as the "Declaration of Perth".
His boldness, at least, was impressive. With one of the Labour Party's founding pledges to grant Home Rule to Scotland long forgotten, the Conservative (and Unionist) Party became the first mainstream UK political party to propose the creation of a devolved Scottish Assembly. Sir Alec Douglas-Home, a former prime minister and Heath's predecessor as leader, was tasked with fleshing out the declaration's bare bones.
But for many Scottish Tories listening in Perth City Hall that day – even committed pro-devolutionists – the announcement came like a bolt from the blue. Never a leader who felt it necessary to take his party with him, Heath had delivered a fait accompli in his zealous quest to modernise the Conservative Party. The party's activist base and 20 Scottish MPs were split down the middle.
But having advocated a more regionally-based style of government on becoming leader in 1965, Heath had taken that aim to its next logical step. There was also an obvious political context: seven months earlier, Winnie Ewing had achieved a sensational victory at the Hamilton by-election.
While Labour lurched from crisis to crisis – the pound was devalued 16 days after the result – Heath's response was swift. He summoned leading Scottish Conservatives to his flat at the Albany and agreed plans for a PR offensive against the SNP. And although Conservative Party policy was then strongly opposed to devolution, Heath later wrote in his memoirs that "in the light of the evident shift in opinion since that election (1966], it would have been politically suicidal to stick to our guns".
The Conservatives were also polling badly in Scotland, one survey showing Labour, the Tories and SNP all on roughly 30 per cent of the vote. With the SNP expected to increase its support at the next general election, there was obvious tactical appeal in offering Scottish voters a less radical alternative to full independence while Harold Wilson prevaricated.
Soon The Scotsman got in on the act, outlining its vision of a devolved Scotland in a series of articulate editorials, subsequently repackaged as a pamphlet, How Scotland should be governed.
"If there is a real possibility that Scotland will be dangerous territory for Unionist candidates at the next General Election," read one passage, "Mr Wilson and Mr Heath will surely decide to risk annoying some of their doctrinaire supporters by making major changes in their parties' policy."
By the spring of 1968 that was a risk Heath was prepared to take, encouraged by so-called "Young Turks" in Scotland such as the future Scottish secretary George Younger. The assembly proposal was considered by a meeting of the shadow cabinet on 8 May, 1968. "Though the element of SNP extremism is limited," observed Heath, "there is strong feeling that Scotland should have more say in her own affairs." Quintin Hogg – as Lord Hailsham a future Lord Chancellor – also chipped in, humorously observing that "we are going off very fast … on this. Really it is another Norman Conquest!"
The shadow cabinet eventually approved Heath's Scottish conference speech, fully realising that he had to say something decisive. There followed several decades of constitutional angst for the Scottish Conservatives. Sir Alec Douglas-Home produced a report, "Scotland's Government", in 1970 but Heath's troubled government, distracted by a three-day week, did not consider it a priority. And when Margaret Thatcher ousted Heath as party leader in 1975, she set about lancing the boil of his devolution policy.
There will likely be a few delegates at this weekend's Scottish Conservative conference in Ayr who remember Heath's "Declaration of Perth". They may not have liked it at the time, but four decades of debates about how much say Scotland should have in her own affairs continue. The fact that Annabel Goldie, the Scottish Tory leader, enthusiastically endorses the work of the Calman Commission shows just how far Conservative thinking on devolution has shifted since 1968.
Internationally, a post-1968 political movement did not really develop, although many of its participants on the Left are now serving UK ministers. The Prague Spring later that year also showed the limitations of aspirant small nations in a new, and often harsh, world order. But the result of Heath's speech was more enduring. For Unionists it began 40 years of constitutional navel-gazing; for Nationalists the beginning of a journey which culminated in the creation of a Scottish Parliament more than 30 years later.
• David Torrance's authorised biography of George Younger is published this autumn.