Sir James Sempill (1566 – February, 1625/1626) was the son of John Sempill of Beltrees, and Mary Livingston, one of the "Four Marys", companions of Mary, Queen of Scots.
James Sempill was brought up with James VI under George Buchanan, After a course of instruction with the young king, he completed his education at the University of St. Andrews, and used the title "Mr." or Master on account of his degree, and was also known as "Beltrees" from his family estate.
Sempill assisted James VI in the preparation of his Basilikon Doron. He was on good terms with the Kirk minister Andrew Melville, and caused a furore by showing Melville the contents of Basilikon Doron in advance. Via James Melville they reached the synod of Fife. Sempill later supported Andrew Melville when he was in 1606 committed to the Tower of London. Robert Boyd of Trochrig considered Sempill an enemy of the bishops.
Sempill was Ambassador to England in the years 1591-1600 and was knighted on Christmas Day 1600. Another Scot employed by the King in London, James Hudson, referred to Sempill's youth and inexperience in May 1599. Hudson wrote that Sempill was "a raw piece to employ and one unskilful, only a scholar." 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." Hudson again wrote to Robert Cecil, the English Secretary of State in September 1599, praising Sempill's good nature, and mentioning that his paternal grandmother was English. Hudson added that James Sempill would be "the true Lord Sempill if he had his due."
In August 1599 James Sempill was sent to London to take the place of David Foulis and collect the "gratuity" for James VI, a sum of money which Elizabeth I of England sent to Scotland to support James VI. He became involved in the discussions following the kidnap of Edmund Ashfield by English agent at Leith. In 1601 he was sent to France, and accompanied the Duke of Lennox from Dieppe to London in October.
James Sempill of Beltrees died at Paisley in 1626.
He wrote some theological works:Cassander Scotiana to Cassander Anglicanus (1616);
Sacrilege sacredly handled (1619), written against Joseph Justus Scaliger and John Selden;
Sacrilege saved by Cassander (1619);
An Answer to Tilenus' Defence of the Bishops and the Five Articles (1622). This was written against Daniel Tilenus at the suggestion of Andrew Melville.
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). Seven poems, chiefly of an amorous character, are printed in T. G. Stevenson's edition of The Sempill Ballates.
His wife was Egidia or Geillis Elphinstone of Blythswood. They had two sons, Robert Sempill the younger and George (who died young), and five daughters, of whom Marion was married to Colin Campbell of Ardkinlas, and Margaret to Walter Macfarlane of Macfarlane.