Lord Maitland's son John Maitland was created the 1st Earl of Lauderdale in 1624. His son was John Maitland, Duke of Lauderdale (1616–1682), one of the most important Scottish figures of the late 17th century, being appointed Secretary of State for Scotland in 1660, a position carrying unrivalled power and influence. He employed the architect Sir William Bruce to transform the castle into a residence suitable for conducting the affairs of state. Between 1670 and 1676 the substantial alterations included the addition of the two front towers and the grand staircase, in addition to extensive internal modifications creating lavish staterooms with magnificent plasterwork ceilings. Lauderdale had Bruce retain much of the castle's earlier fabric giving it an external aura of antiquity, while the interiors met the highest fashion in seventeenth century planning and furnishing. This allowed Lauderdale to revere the antiquity of his family residence at the same time as living in high contemporary fashion.