During the Wars of the Three Kingdoms he rose to be a colonel in the royalist army, was arrested in August 1647 at Kingston-on-Thames, and was imprisoned in Windsor Castle.
Fighting a duel with Major Nicholas Armorer in Brabant, he was sent in June 1652 by Buckingham to London with a sealed letter directed to Oliver Cromwell.
The Council of State refused to listen to him, gave him back the letter, and ordered him to leave the country within a certain time; but he is also reported to have had a courteous extended interview with Cromwell.
[3][4] Leighton continued his involvement with Royal Africa Company affairs, eventually becoming the secretary of the corporation through the influence of the Duke of York, who would become the future King James II.
Leighton contrived to turn out of the Dublin corporation the recorder and several of the principal aldermen who were known to be opposed to Catholics.
In 1675 he accompanied Berkeley on his embassy to France, and, while arranging for the restitution of vessels captured by French privateers, took bribes on all sides.
[1] Leighton died in the parish of St Andrew, Holborn, on 9 January 1685, and was buried in the church of Horsted Keynes, Sussex, leaving a daughter Mary.