Arthur Gerald Wellesley, Earl of Mornington, is the great-great-grandson of what  last German Emperor ("Kaiser") and King of Prussia?
Wilhelm II, German Emperor Wilhelm II or William II (German: "Friedrich Wilhelm Viktor Albert von Preußen", English: Frederick William Victor Albert of Prussia; 27 January 18594 June 1941) was the last German Emperor ("Kaiser") and King of Prussia, ruling the German Empire and the Kingdom of Prussia from 15 June 1888 to 9 November 1918. He was the eldest grandchild of the British Queen Victoria and related to many monarchs and princes of Europe.
Egerton family The Egerton family (pronunciation: ""edger-ton"") is a British aristocratic family. Over time, several members of the Egerton family were made knights, baronets and peers. Hereditary titles held by the Egerton family include the dukedoms of Bridgewater (1720–1803) and Sutherland (since 1963), as well as the earldoms of Bridgewater (1617–1829), Wilton (1801–1999) and Egerton (1897–1909). Several other members of the family have also risen to prominence.