In 1641, after the Scottish army had invaded England and occupied Newcastle upon Tyne, the Sutherland Laird of Duffus joined the Earl of Sutherland on a visit to the camp but returned with the earl's train to attend the Parliament at Edinburgh in July, 1641. The Laird of Duffus was also at Edinburgh in August 1641, to greet Charles I of England when he paid a visit to Scotland and the Laird of Duffus appears to have been knighted by the King as in 1643 he is styled as Sir Alexander, appearing on various Parliamentary Committees. He was also a Commissioner for Sutherland in 1646.[3]
He was a supporter of the National Covenant and as a result his estates, probably those in Morayshire, were attacked by the Royalists. Therefore, in 1647, he petitioned to Parliament for compensation of £10,000 Scots to be paid to himself and £2000 Scots to be paid to his uncle, James Sutherland, by the English Parliament.[3]
His wife died in 1648 and so he traveled abroad through France and Holland, returning with Charles II of England on June 24, 1650.[2][3] When he attended the Parliament held at Perth in 1651, he was styled as a Peer with the title of Lord Duffus.[2][3]
He was not part of the Scottish army that subsequently marched to England, but was sent from Stirling to Perth to defend it from the attack of Oliver Cromwell, but was forced to surrender the town which he had only occupied for twelve hours previously with just 600 men.[2][3]
After the Restoration of Charles II, Lord Duffus went to London where he received letters from Archibald Campbell, 9th Earl of Argyll, then the Lord of Lorne. However, one of these letters was intercepted by John Middleton, 1st Earl of Middleton who was then the Lord High Commissioner to the Parliament of Scotland and Lord Duffus admitted that the author of the letter, which was written anonymously, was the Lord of Lorne who was as a result condemned to death for High treason.[3]
Alexander Sutherland, 1st Lord Duffus died on August 31, 1674.[2][3]