Mure had entered Parliament in 1742 as an Opposition Whig, but by 1754 had become a regular Government supporter. On at least one occasion in 1755 he was prepared to go out of town rather than vote against Administration.
By this time you begin to suspect that I have opposed the subsidies and incline to a very small minority. You are in the right, and if you come here at all this winter you will think twice and hear all before you take a determined part ... Pitt shines more and rises higher than ever ... I could heartily wish you had been here, and I believe you would either have chosen your part right or else— .
Mure eventually joined Pitt in opposition and subsequently supported his brief Administration of 1756-7.
Mure was neither an orator nor ambitious of office, but excelled as a negotiator in business and constituency affairs. In 1757 he offered to undertake the management of Bute’s neglected Scottish estates. Bute wrote, 7 Aug. 1757:
What words am I to make use of to express to you the warmth I feel for the friendly part you are acting for me. Almost a stranger to me, and you enter into all the trouble of my business, into all my interests as if we had from our cradles trod the paths of life together ... I love and value you; I hold myself greatly obliged to you.
From this time Mure became wholly devoted to Bute. It was he who in 1758 first proposed that Bute should secure Ayr Burghs for his own and the Prince of Wales’s interest, and thus precipitated the quarrel with Argyll, who, in retaliation, encouraged an opposition to Mure in Renfrewshire.
Although Mure supported the Scottish militia agitation and was a member of the parliamentary committee to prepare the bill, he was chiefly concerned throughout 1760 in election negotiations and in preventing a complete rupture with Argyll. By the end of the summer he had persuaded Argyll to declare for him in Renfrewshire, and thus made his re-election certain. His opponents hoped he might be removed from the scene by promotion to the Scottish bench,
By the death of Argyll, the management of Scottish affairs passed to Bute, who made Mure his principal adviser in Scotland; and when James Stuart Mackenzie took over Scottish affairs in the autumn of 1761, Mure continued to act as his lieutenant and confidant in all public and private business. Before his resignation Bute secured for Mure the reversion of the receivership general of Jamaica.
He died 25 Mar. 1776.
