In 1567 James Mosman was converting a piece of Mary, Queen of Scots' jewelry when she was imprisoned in Lochleven Castle. He remained loyal to Mary when she was exiled in England. Mosman worked in Edinburgh Castle with James Cockie making coins for Mary's supporters who held the castle during the 'Lang Siege'. The two goldsmiths valued the jewels of Mary, Queen of Scots which remained in the castle, so they could be used as security for loans.