Question: What British Prime Minister committed the British Conservative Party to supporting Scottish devolution through the Declaration of Perth?

Context articles: Conservative Party (UK)
92 Group
Federation of Conservative Students
Bonar Law
Conservative Party (UK) leadership election, 1997
Edward Heath
Stephen Crabb
Declaration of Perth
Margaret Thatcher
Peelite

The Conservative Party, officially the Conservative and Unionist Party, is a centre-right political party in the United Kingdom.
 It is currently the governing party, having been so since the 2010 general election, where a coalition government with the Liberal Democrats was formed.
 In 2015, the Conservatives led by David Cameron won a surprise majority and formed the first Conservative majority government since 1992.
 However, the 2017 snap election on Thursday 8 June resulted in a hung parliament, and the Conservatives lost their parliamentary majority.
 They are reliant on the support of a Northern Irish political party, the Democratic Unionist Party (DUP), in order to command a majority in the House of Commons through a confidence-and-supply deal.
 The party leader, Theresa May, has served as both Leader of the Conservative Party and Prime Minister since 13 July 2016.
 It is the largest party in local government with 9,237 councillors.
 The Conservative Party is one of the two major contemporary political parties in the United Kingdom, the other being its modern rival, the Labour Party.
 The Conservative Party's platform involves support for free market capitalism, free enterprise, fiscal conservatism, a strong national defence, deregulation, and restrictions on trade unions.
The 92 Group is a right-wing grouping within the British Conservative Party.
 They are so named because they would meet at Conservative MP Sir Patrick Wall's home, 92 Cheyne Walk in Chelsea, London.
 It was founded in 1964 in order to "keep the Conservative Party conservative" and membership is by invitation only.
 During the period of Margaret Thatcher's leadership of the Conservative Party it was a prominent supporter of her policies.
 During John Major's premiership it became a focus for Thatcherite MPs dissatisfied with his leadership and was prominent in supporting John Redwood's unsuccessful candidacy against John Major for the leadership of the Conservative Party in 1995.
The Federation of Conservative Students (FCS) was the student organisation of the British Conservative Party from the late 1940s to 1986.
 It was created to act as a bridge between the student movement and the Conservative Party.
 In its final years it became known colloquially as "Maggie's Militant Tendency", in reference to then Prime Minister Margaret Thatcher and to Militant, an entryist group active in the Labour Party at the time.
 The FCS was then broken up by the Chairman of the Conservative Party, Norman Tebbit, after one of its members had accused previous former Prime Minister Harold Macmillan of war crimes in extraditing Cossacks to the Soviet Union.
 The FCS was replaced by the Conservative Collegiate Forum.
Andrew Bonar Law (16 September 1858 – 30 October 1923), commonly called Bonar Law ( ), was a British Conservative Party politician and Prime Minister.
 Born in the British colony of New Brunswick (now in Canada), he is the only British prime minister to have been born outside of the British Isles.
The 1997 Conservative Party leadership election was triggered in the British Conservative Party when John Major resigned on 2 May 1997, following his party's defeat at the 1997 general election, which ended 18 years of Conservative Government of the United Kingdom.
 Major had been Conservative leader and Prime Minister since November 1990.
Sir Edward Richard George Heath, (9 July 1916 – 17 July 2005), better known as Ted Heath, was a British politician who served as Prime Minister of the United Kingdom from 1970 to 1974 and Leader of the Conservative Party from 1965 to 1975.
 He was a strong supporter of the European Communities (EC), and after winning the decisive vote in the House of Commons by 336 to 244, he led the negotiations that culminated in Britain's entry into the EC on 1 January 1973.
 It was, says biographer John Campbell, "Heath's finest hour".
 Although he planned to be an innovator as Prime Minister, his government foundered on economic difficulties, including high inflation and major strikes.
 He became an embittered opponent of Margaret Thatcher, who supplanted him as party leader in 1975.
Stephen Crabb{'1': ", '2': ", '3': ", '4': "} (born 20 January 1973) is a British Conservative Party politician.
 He has been the Member of Parliament for Preseli Pembrokeshire since the 2005 general election and was Secretary of State for Work and Pensions from March 2016 until July 2016, when Prime Minister David Cameron resigned and Theresa May took over as Prime Minister and Leader of the Conservative Party.
 He has previously been a government whip, a junior minister for Wales and the Secretary of State for Wales.
The Declaration of Perth was a statement made by British Conservative Party leader Edward Heath on 18 May 1968, at the party conference in Perth, Scotland, which committed the party to supporting some form of Scottish devolution.
Margaret Hilda Thatcher, Baroness Thatcher, {'1': ", '2': ", '3': ", '4': "} (née Roberts ; 13 October 1925 – 8 April 2013) was a British stateswoman who was Prime Minister of the United Kingdom from 1979 to 1990 and Leader of the Conservative Party from 1975 to 1990.
 She was the longest-serving British prime minister of the 20th century and the first woman to have been appointed.
 A Soviet journalist dubbed her the "Iron Lady", a nickname that became associated with her uncompromising politics and leadership style.
 As Prime Minister, she implemented policies that have come to be known as Thatcherism.
The Peelites were a breakaway faction of the British Conservative Party, existing from 1846 to 1859, who joined with the Whigs and Radicals to form the Liberal Party ('Liberal' referring to their position on economic matters).
 They were called "Peelites" because they were initially led by Sir Robert Peel, who was the British Prime Minister and Conservative Party leader in 1846.