Ashton was clerk of the closet to Mary of Modena, the wife of James II, and, after the revolution of 1688, showed himself ardently devoted to the interests of his exiled master and mistress.
He appears to have held a commission of captain or major in the army, and to have been an intimate friend of Dr. Thomas Cartwright, who was bishop of Chester from 1686 to 1689, and a zealous supporter of the Stuart dynasty.
Viscount Preston undertook to visit St. Germains with the papers requisite to obtain support for the conspiracy, and Ashton promised to arrange the journey and bear him company.
Ashton, who was described in the indictment as 'late of the parish of St. Paul's, Covent Garden,' declared that he was about to visit France to learn from the exiled queen how she proposed to settle certain unpaid debts with her London tradesmen, for many of which he, as her late clerk, was held responsible, and he called witnesses in support of his assertion.
Before his death he handed to the sheriff a paper declaring himself a Protestant, and happy in losing his life in James II's service, from whom he had received favours 'for sixteen years past.'