[2] A staunch adherent of the Royal Family during the Civil Wars, on 10 June 1661 he was created Lord Bellenden,[3] was made Treasurer-depute, and was placed on the privy council of Scotland.
[3] In 1662, John Maitland, 1st Duke of Lauderdale, on the advice of his brother, managed to secure Bellenden's interest in his struggle with John Middleton, 1st Earl of Middleton and faction over religious policy; and he is from that time one of his most frequent correspondents.
[3] When the treasurership was taken from John Leslie, 7th Earl of Rothes in 1668 and was put into commission, Bellenden was one of the commissioners.
He was then in failing health, and was noted for his overbearing manners at the treasury board meetings, especially when, as was the case, his own accounts as treasurer-depute were called in question, or when any matter of precedence was in dispute.
[3] As Bellenden was unmarried and childless, on 14 April 1671, he resigned his peerage in favour of his first cousin twice times removed, Hon.