By his father young Erskine had been educated in the principles of the covenanters, and at an early period distinguished himself by his opposition to the administration of Lauderdale.
In this he was strongly supported by his wife, Catherine, youngest of the two daughters and coheiresses of Sir William Stewart of Kirkhill.
of which he paid 1,000l., and after an attempt to obtain a remission for the balance he was, 5 August 1675, committed to the prison of Edinburgh, where he remained for four years.
In 1679 the king's forces in their march westwards went two miles out of their way to quarter on his estates of Kirkhill and Uphall, West Lothian.
This proceeding gave great offense to the Scottish privy council, who sent a letter to the king accusing Cardross of misrepresentation, the result being that all redress was denied him.
On 28 October 1685 his estate in Scotland was exposed to sale by public roup, and was bought by the Earl of Mar at seventeen years' purchase.