 It is not clear how Douglas came to possess Tantallon, but in correspondence of 1374, he refers to "our castle of Temptaloun". Douglas may have been made castellan of Tantallon, as a tenant of Isabella, Countess of Fife, and it appears that he built the present castle either shortly before, or shortly after, his elevation to the peerage, to reflect his new-found status. It was intended as a status symbol, although it followed the medieval curtain wall type, which at the time was becoming outmoded and superseded by the tower house. The Douglases continued to hold the lands of Tantallon as tenants of Robert Stewart, Earl of Fife (c.1340-1420), from 1371 until 1372, when he resigned the title in favour of his son Murdoch. Tantallon was the home of William Douglas'sister-in-law and mistress, Margaret Stewart, Countess of Angus, the mother of his illegitimate son George Douglas (1380 – 1403). In 1377, the Earl made his close friend, Alan de Lawedre of The Bass, Constable of Tantallon Castle, an office he held until at least 1389. In 1388, when the 2nd Earl of Douglas died, the Earl of Fife claimed the lands of Tantallon, and confirmed the Countess' right to live there. Several attempts were made to dislodge the Countess, but the agreement was formalised by parliament in April 1389, and George Douglas was recognised as Earl of Angus, as his mother's heir.
