Barclay provided drugs and medicines for the Scottish royal family and their physicians John Naysmyth, Gilbert Primrose, and Martin Schöner.
[4] Barclay also sold sugar confectionery, the family of William Douglas of Lochleven bought boxes of wet and dry confections.
He was allowed bail or caution for future loyalty at £1,000 Scots, guaranteed by the textile merchant Robert Jousie and Barclay.
[7] Edinburgh burgh hosted a banquet for the queen's brother, Ulrik, Duke of Holstein, on 2 May 1598 at the house of Ninian MacMorran at Riddle's court.
[9] In May 1601 he supplied plasters, oil, and liniments to James VI who had hurt his arm, and in the same month provided medicines for Anne of Denmark and Prince Charles.