From his youth, Fletcher was trained in political discretion by his father, Lord Milton, ‘confidential friend and deputy’ to Archibald, Duke of Argyll in the management of Scotland.
Over the Scottish militia bill of 1760, on which Argyll’s attitude was equivocal, Fletcher, under his father’s direction, took an active part, being one of the inner group nominated by the Edinburgh committee (under Milton’s presidency), to concert how the bill should be brought into Parliament.
Owing to Argyll’s dislike of letter-writing Fletcher was entrusted with much confidential business. In 1760 he was employed by Argyll in an attempt to patch up his quarrel with Bute. Newcastle wrote to Hardwicke, 6 Sept. 1760:
[Argyll] told me ... that he had sent Fletcher to my Lord Bute, his Lordship having objected extremely to Mr. [Samuel] Martin. That Fletcher had not succeeded better, that he complained to him of sending Mr. Martin and letting the English into their dispute.
After Argyll’s death, although Bute proffered friendship,
Fletcher supported the Bute Administration on the peace, and the Grenville Administration on general warrants, but after 1765 practically ceased to attend Parliament. He was absent in Scotland from the divisions on the repeal of the Stamp Act in February 1766, and does not appear in any subsequent division list. In January 1767 Townshend classed him as absent. He maintained a connexion with Grenville, to whom he explained on 9 Mar. 1768
Fletcher retired to his Saltoun estate, devoting himself to agricultural improvement and the cultivation of his nurseries of exotic trees and shrubs, which had long been famous. He died 24 May 1779.
