A royal charter of 8 February 1543 noted Thomas as the uncle of the reformer John Erskine of Dun, who was married to a French lady-in waiting of Mary of Guise, Barbara Berlay.
[7] As a reward for his services at home and abroad, in August 1531 Thomas was given the important task of keeping, repairing, and garrisoning Tantallon Castle, which James V of Scotland had obtained from the exiled Earl of Angus.
[16] However, at this time James V's advisors and the Duke of Albany hoped to gain political advantage by contracting the King's marriage to Catherine de' Medici the young Duchess of Urbino.
On his way to Rome to meet Albany in December 1531 to further the Urbino marriage with Pope Clement VI,[17] Erskine was shipwrecked on the French coast.
Erskine's instructions may have included asking Albany to press Clement VI to allow James V to tax the church in Scotland.
[20] Initially, Francis I organised a substitute bride: Erskine was at Cremieu on 6 March 1536 when the contract was made for James V to marry Mary of Bourbon, daughter of the Duke of Vendôme.