General Peregrine Bertie, 3rd Duke of Ancaster and Kesteven PC (1714 – 12 August 1778), styled Lord Willoughby de Eresby from 1715 to 1723 and Marquess of Lindsey from 1735 to 1742, was an English peer.

Elizabeth was the daughter of William Blundell of Basingstoke, Hampshire, whose mother, Alice Blunden, was the alleged victim of a notorious premature burial.

Mary was the daughter of Thomas Panton of Newmarket, who was an equerry to King George II and master of the Thurlow Hunt.

They had six children:[3] Lord Ancaster died on 12 August 1778 and was succeeded in his titles by his only surviving son, Robert.

After Robert's death in 1779 without a male heir, Peregrine's younger brother, Brownlow, succeeded to the dukedom.