The Earl of Eglinton had a brother, Sir John Seton of St Germains in East Lothian, who married Margaret Kellie.
[2] John Seton, the letter writer, was a Lieutenant of the French Royal Guard, the Gardes Écossaises.
[7] Sir John Seton of Carchunoth had brought 1,200 Scottish recruits from the Dutch Republic to Bohemia in 1619.
The governor of Hagelburg (in 1638), Colonel Thomas Thomson, another officer of the Gardes Écossaises, later partnered with John Clerk of Penicuik and bought soft furnishings in Paris for the Earl of Lothian.
The commander in Bohemia was a member of the Seton of Touch branch of the family, and a more distant cousin of the Earl of Eglinton than the son of the lairds of Carriston or Kylesmure.
[14] The other Sir John Seton wrote from France in November 1634, having hosted Eglinton's sons in Paris.
One of the Eglinton children, Henry, was left in London in the care of the courtier and architect David Cunningham of Auchenharvie.