Margaret Masterton or Maistertoun was employed in 1594 at Stirling Castle as the nurse of Prince Henry, the son of James VI and I and Anne of Denmark.^[1]

She was a daughter of Janet Couston and Alexander Masterton of Bad in Perthshire, Masterton near Dunfermline, and Parkmill in Clackmannanshire.^[2]

She married a lawyer, James Primrose of Barhill, Culross.^[3] He kept a record of his legal work, known as a "Protocol Book", which is preserved by the National Records of Scotland.^[4] She was sometimes known as "Mistress Primrose" and received annuity payments from Prince Henry under that name.^[5] Their son George Primrose was a clergyman at Hereford Cathedral and preacher at the Eignbrook Chapel in 1662.^[6]

She may have been the wet-nurse to the Prince described by George Nicholson who became ill and was replaced in January 1595 by the wife of Henry Murray, a Stirling burgess.^[7] The baby would not feed unless his first nurse was present.^[8]