His eldest son, James, Earl of Angus, born in 1671, in 1689 raised for the service of the nation, in one day, a regiment of eighteen hundred men, now called the 26th foot or Cameronians, of which he was appointed colonel, 19 April of that year.
His half brother, William, also bore the title of earl of Angus, but died an infant in 1694.
The story of the end of the marriage between James Douglas and Barbara Erskine is immortalized in the popular ballad Waly Waly, which is known by many alternative titles (e.g. Jamie Douglas, When Cockleshells Turn Silver Bells, Water Is Wide) with many alternative lyrics and melodies.
The marquis, a man of profligate conduct, was subsequently led by his factor, Lowrie of Blackwood (said to have been a rejected suitor of the lady), to suspect his marchioness of infidelity, and they were consequently separated, after she had born him one child.
The prose reality of all this was, that the marchioness by and by obtained a decree of the Privy Council, allowing her a provision out of her husband’s estate.