This branch of the Seton family had long served the Bruces in Yorkshire, Cumberland and Scotland.
John performed fealty to King Edward I of England at Berwick on 28 August 1296.
Seton was present on 10 February 1306 when Sir John Comyn, Lord of Badenoch was stabbed by Robert de Brus in Greyfriars Church, Dumfries.
[1][2] A letter of excommunication was issued naming the Robert de Brus, Earl of Carrick and three other knights—Sir Alexander Lindsay, Sir Christopher Seton and his brother John—as John Comyn's murderers.
He was executed on the basis that he was a witness to the murder of John Comyn, Lord of Badenoch by Robert de Brus, Earl of Carrick at Dumfries and for holding Tibbers Castle against Edward I.