In 1559 James's political activities and allegiances during the Scottish Reformation were at first equivocal, but in February 1560 he signed the Treaty of Berwick which invited an English army into Scotland to expel the Catholic regime of Mary of Guise. He took part in the unsuccessful embassy to England in November 1560 to treat for the marriage of Elizabeth I of England to James Hamilton, 3rd Earl of Arran. On their way back from London Grey de Wilton hosted the Scottish ambassadors at Berwick and gave the Earl of Morton a personal tour of the latest fortifications.