[1] Sempill was brought up with James VI under George Buchanan at Stirling Castle in the royal household supervised by Annabell Murray, Countess of Mar.
Another Scot employed by the King in London, James Hudson, referred to Sempill's youth and inexperience in March 1599.
[3] Roger Aston, an English courtier of James VI, wrote in August 1599 that "Beltries was plain and honest, and by the means of Sir George Elphinstone (of Blythswood) whose sister he married, he may do good offices."
[5] A Scottish servant of Lady Kildare named Dicksoun ingratiated himself with Sempill, and said she had spoken in favour of the king's succession to the English throne at dinner with the Lord Admiral.
[8] On his return to Scotland, in April 1600, Anne of Denmark asked him what Elizabeth had said about her, and she disbelieved him at first, based on the reports of others.
[13] Back in Scotland, in April 1602 Anne of Denmark asked him to mention her in a letter to Robert Cecil.
She told Sempill that Sir Thomas Erskine of Gogar had been the author of slanders against her which were current in France and England.
She had had an offer from a courtier to destroy the career of the Earl of Mar if she undermined the Duke of Lennox, which she knew how to do, and understandably wanted Sempill to keep this secret.
[15] On 3 February 1603 James gave him a jewel which had belonged to Mary, Queen of Scots for his good service abroad and at home, and faithful conduct of diplomatic negotiations.
He wrote some theological works: He is now chiefly remembered for the poem The Packmans Pater Noster, a vigorous attack on the Roman Catholic Church.
An edition was published at Edinburgh in 1669 entitled A Pick-tooth for the Pope, or the Packmans Pater Noster, translated out of Dutch by S. I. S., and newly augmented and enlarged by his son R. S. (reprinted by Paterson).