William Sackville, 10th Earl De La Warr

William Herbrand Sackville, 10th Earl De La Warr (16 October 1921 – 9 February 1988) was a British peer. He inherited the earldom on 28 January 1976 on the death of his father Herbrand Edward Dundonald Brassey Sackville, 9th Earl De La Warr.

Earl De La Warr was educated at Eton College, and fought in World War II, attaining the rank of Captain in the Parachute Regiment of the British Army. After the war, he married Anne Rachel Devas on 18 May 1946, and had three children:

In the autumn of 1987, the earl offered to sell Ashdown Forest, the real-life setting of the Winnie-the-Pooh stories, to the East Sussex County Council at a below-market price of £1.2 million for the 6,500 acre property. As young children, the future earl and Christopher Robin Milne had played together there. Milne himself joined conservationists to prevent the forest from being sold piecemeal to private owners, and to oppose an application by BP to drill for oil there. The sale to the county council was concluded after the earl's death, making the forest public land.

On 9 February 1988, at age 66, Earl De La Warr died after falling under a train at the St. James's Park station of the London Underground. An inquest ruled the death to be a suicide, with a jury finding that the earl had been "anxious and upset over hurricane damage to his estate."