Douglas’s father was ‘the chief director of his friend the Duke of Queensberry’s country affairs and parliamentary interest in the county of Dumfries’ but ‘Sir John was no economist ... he run aground and as he likewise had been nibbling to serve the Jacobite party ... this added to the distraction and confusion of his affairs.’
In 1768 Queensberry brought him into Parliament where he supported Administration, but is not known to have spoken. His father, imprisoned for debt in January 1778, died in November, shortly after the death of his patron Queensberry, who had long treated William as his eventual heir to the marquessate of Queensberry, failing male issue by his immediate successor Lord March.
The Duke shortly before his death, having a warm attachment to my nephew Sir William, whom he sincerely loved from his proper behaviour to him while in Parliament, and considering that he had [children] ... to provide for, he left him £16,000 in money for their behalf ... On the worthy Duke’s death ... this new unkindly and ungenerous Duke refused to pay the money ... My nephew seeks my approbation for suing the Duke in the court of session.
And at the general election of 1780 the new Duke refused to return him to Parliament.
His action before the court of session for £20,000 (£16,000 plus interest) was successful; and on 30 Apr. 1783 Queensberry’s appeal was dismissed by the Lords. Sir William was so overjoyed by the news that he had an apoplectic fit while playing with his children, and died 16 May 1783.
