Returning to England with a brilliant reputation he was well received by King Charles II, who appointed him a member of the Privy Council of Scotland, and give him command of the East Lothian Regiment of Foot against the Covenanters in 1666, following which he defeated the rebels at Pentland, and also, in 1679 he again commanded the same regiment "upon his own charges, with all his vassals, in noble equipage, in his Majestie's army of 14,000 men", at Bothwell Bridge, were the rebels were totally defeated.
[1] In 1682 he was appointed Sheriff of Haddingtonshire, and in May of the same year he accompanied the Duke of York from London to Edinburgh in the frigate Gloucester, which was wrecked,[2] with great loss of life, on Yarmouth Sands.
As a learned individual, Professor Sinclair presented him with a curious and rare work entitles Satan's Invisible world discovered – or A choice collection of relations anent devils, spirits, witches, and apparitions in 1685.
The lengthy 'Epistle Dedicatory' is in a vein of exaggerated praise, somewhat relieved by a description of the Earl's coal-mining operations, in which Sinclair introduces the name of Athanasius Kircher, the Jesuit, who founded the Kircherian Museum in the Roman College, at Rome, and was one of the first natural philosophers and scientists of the age.
Alexander Nisbet says of this nobleman that "he imitated the extraordinary loyalty of his ancestors; none of them having ever been guilty of treason or rebellion, nor addicted or avarice, nor found with lands of the Church in their possession".