Robert Bertie, 1st Duke of Ancaster and Kesteven, English politician, Chancellor of the Duchy of Lancaster (died 1723)

Robert Bertie, 1st Duke of Ancaster and Kesteven PC, styled 17th Baron Willoughby de Eresby between 1666 and 1701, and known as 4th Earl of Lindsey between 1701 and 1706, and as 1st Marquess of Lindsey between 1706 and 1715, was a British statesman and nobleman.

The Chancellor of the Duchy of Lancaster is a ministerial office in the Government of the United Kingdom. Excluding the prime minister, the chancellor is the highest ranking minister in the Cabinet Office, immediately after the prime minister, and senior to the Minister for the Cabinet Office. The role includes as part of its duties the administration of the estates and rents of the Duchy of Lancaster.

October 20 is the 293rd day of the year in the Gregorian calendar; 72 days remain until the end of the year.