Chiefly through the favour of George Villiers, Duke of Buckingham Cary was appointed to succeed Sir Oliver St John, as Lord Deputy of Ireland. His patent was sealed in March 1622 and he was sworn on 18 September 1622. In office he showed himself both bigoted in his opinions and timid in carrying out a policy which continually dallied with extremes. Although he was conscientious, he was easily offended, and he failed to conduct himself with credit when confronted with any unusual difficulties.