Eldest son of Robert Bertie, 3rd Earl of Lindsey and, his second wife, the Hon. Elizabeth Wharton

Grimsthorpe Castle, Lincolnshire

Entered Parliament as MP for Boston in 1685 Commissioned captain of an independent troop of horse raised to suppress the Monmouth Rebellion on 20 June 1685 1688 - took part in the northern rising led by his kinsman, the Earl of Danby, in favour of William of Orange. He was rewarded with the chancellorship of the Duchy of Lancaster in 1689, a post which enabled him to secure a seat at Preston at the general election of 1690 He moved to the House of Lords after receiving a writ of acceleration as Baron Willoughby de Eresby He inherited the earldom of Lindsey on his father's death in 1701, and was invested a Privy Counsellor one month later. Along with the Earldom of Lindsey, he also inherited the offices of Lord Great Chamberlain and Lord Lieutenant of Lincolnshire, both of which he would hold until his death.

1706 - created Marquess of Lindsey 1715 - created Duke of Ancaster and Kesteven

In 1715, he employed Sir John Vanbrugh to design a baroque front to his house at Grimsthorpe to celebrate his ennoblement as first Duke of Ancaster and Kesteven