John Seton of Seton

Source= http://en.wikisource.org/wiki/1911_Encyclop%C3%A6dia_Britannica/Seton

SIR John of Seton (d. c. 1441) was taken prisoner at Homildon Hill in 1402. He was hostage in England for the earl of Douglas in 1405, and again in 1423 for James I. He married Lady Janet Dunbar, daughter of the 10th earl of March. His son Sir William was killed at Verneuil, fighting on the French side, leaving as heir George (d. 1478), 1st Lord Seton, who was created a lord of parliament in 1448 as Lord Seton.

Source= http://etree10.archive.org/stream/historyoffamilv100seto/historyoff...

Among the hostages nominated for the release of James 1., by the treaty  of 4th December 1423, was 'Johannes Dominus de Setoun, miles,  vel filius ejus et haeres,' his annual revenue being then estimated  at 600 merks. He was also one of the guarantees of the treaty  for the King's release, 28th March 1424. He is said to have died  in 1 44 1, and was buried at Seton Church, ' in the yle foundit be  his moder.' By his wife, Lady Janet, daughter of George, tenth  Earl of March, 1 he had a son William, and two daughters, of  whom Christian (who is not mentioned by Sir Richard Maitland)  married Norman Leslie of Rothes, under a papal dispensation,  on the ground of consanguinity (fourth degree), obtained in  December 1415 ; while Janet married Robert Keith, eldest son  of William, first Earl Marischal, by whom she had no male issue.  Douglas states that Lord John appears to have had a second wife,  who was alive in 1449; but this is not very consistent with  Sir Richard Maitland's circumstantial statement regarding the  marriage of the mother of his son and successor (Lady Janet  Dunbar) to a second husband, in the person of the laird of  Johnston in Annandale, 2 called by Douglas 3 Sir Adam  Johnston of that ilk.