On 5 July 1746, he was created Earl Clinton, with normal remainder to the heirs male of his body and Baron Fortescue, of Castle Hill in the County of Devon, with special remainder, failing heirs male of his body, to his half-brother Matthew Fortescue.

In 1859 he was summoned to the House of Lords through a writ of acceleration in his father's junior title of Baron Fortescue.

On his death the titles passed to his eldest son Hugh Fortescue, 5th Earl Fortescue (1888–1958), a Conservative politician who served as Captain of the Honourable Corps of Gentlemen-at-Arms (Chief Government Whip in the House of Lords) in 1945 and from 1951 to 1958.

Sir Seymour John Fortescue (1856–1942), second son of the third Earl, was a captain in the Royal Navy and also served as Serjeant at Arms in the House of Lords.

Charles Grenville Fortescue (1861–1951), sixth son of the third Earl, was a brigadier-general in the army.

The more grandiose former seat Castle Hill, Filleigh, North Devon, rebuilt as a Palladian mansion by Hugh Fortescue, 1st Earl Clinton (1696–1751), has been since the death of the 5th Earl in 1958, the property and residence of descendants in the female line.

[3] The heir presumptive is the present holder's first cousin John Andrew Francis Fortescue (born 1955).