Married to Katherine Cunningham, dau of Sir William Cunningham. The couple had at least three children, Margaret (d. 1801), Jane and Quintin (1769-1805). Owner of Berboth (Barbeth?), Straiton and Dunaskin, Dalmellington.
McAdam was a relation of famed engineer and inventor John Loudon McAdam (1756-1836), and he was himself a noted agricultural improver.
McAdam was a close friend of the Boswells of Auchinleck. James Boswell and James Chalmers dined with the Laird at his seat at Berboth, on September 14, 1762. Boswell described it as "an agreeable place enough of the kind, the fields being brought to a good verdure and the rising ground planted. We were entertained with a hearty welcome". The Laird of Camlarg, a nephew of McAdam's, was present as well. The conversation touched mainly upon subjects concerning practical agriculture, so when Boswell had "exhausted all [his] little stock of country conversation [and] no other could be well understood, at least could not please, [he] was heartily wearied".1
- 1Quotations from Boswell's Journal of my Jaunt.