Earl of Clare was a title of British nobility created three times: once each in the peerages of England, Great Britain and Ireland.
The Norman family who took the name 'de Clare' became associated with the peerage as they held, at differing times, three earldoms (Gloucester, Pembroke and Hertford).
[4] The three were granted equal parts of the English possessions, but Despenser received the entire lordship of Glamorgan in Wales, politically the most important of the de Clare lands.
Some contemporary sources called them "Earls of Clare", but many modern historians treat this as if it were a "styled" (self-assumed) title.
[9] However, John Burke in 1831 states that prior to the 1624 creation, Robert Rich, Earl of Warwick, was to be created Earl of Clare, but that it was refused by the crown lawyers, "on a solemn declaration, that it was a title peculiar to the royal blood and not to be conferred upon a subject.
"[10] The title of Earl of Clare was formally created by letters patent in the peerage of England on 2 November 1624 for John Holles.
Their daughter, Lady Margaret Cavendish Harley, who married William Bentinck, 2nd Duke of Portland.
The following year, on 2 August 1715, he was further created Marquess of Clare and Duke of Newcastle, with remainder to his brother the Rt.
In 1756, he was created Duke of Newcastle Under Lyne with remainder to his nephew, Henry Fiennes-Clinton, 9th Earl of Lincoln.