The title was suspended for Ernest's pro-German activities during World War I under the Titles Deprivation Act 1917, as it was for his son. Under the Act, the lineal male heirs of the 3rd Duke of Cumberland and Teviotdale have the right to petition the British Crown for the restoration of his peerages. To date, none has done so. The present heir is Prince Ernst August of Hanover (born 26 February 1954), great grandson of the 3rd Duke and current head of the House of Hanover. He is the senior male-line descendant of George III of the United Kingdom.
Dukes of Cumberland and Teviotdale
After the Union of Great Britain, the Hanoverian kings liked to grant double titles (one from one constituent country, one from another) to emphasise unity.
Prince William Augustus (1721–1765) Duke of Cumberland, Marquess of Berkhamsted, Earl of Kennington, Viscount Trematon, Baron Alderney
Dukedom of Cumberland (3rd creation), Marquessate of Berkhamsted, Earldom of Kennington, Viscountcy Trematon (1st creation), and Barony Alderney extinct, 1765