The title of Earl of Middlesex has been created twice in the Peerage of England. The first creation was in 1622 for Lionel Cranfield, the Lord High Treasurer, who had been created Baron Cranfield the year before. Both titles became extinct in 1674. The next creation was for Charles Sackville, Lord Buckhurst, son of Frances, daughter of the 1st Earl of Middlesex and sister of the second and third Earls. He was created Earl of Middlesex and Baron Cranfield in 1675. He succeeded his father as 6th Earl of Dorset in 1677, and the two earldoms remained united until the death in 1843 of the 5th Duke of Dorset, 11th Earl of Dorset and 6th Earl of Middlesex, when all the titles became extinct.
The next creation was for Charles Sackville, Lord Buckhurst, son of Frances, daughter of the 1st Earl of Middlesex and sister of the second and third Earls.
He succeeded his father as 6th Earl of Dorset in 1677, and the two earldoms remained united until the death in 1843 of the 5th Duke of Dorset, 11th Earl of Dorset and 6th Earl of Middlesex, when all the titles became extinct.
Charles Sackville, 1st Earl of Middlesex (1638-1706), succeeded as 6th Earl of Dorset
Richard Burgh, earl of Clanricard of the kingdom of Ireland, was created by king James the first 3 April 1624 lord Somerhil and viscount Tunbridge, and by king Charles the first earl of Saint Albans, which title became extinct upon the death of Ulic, second earl of Saint Albans, 1659.
George Montagu, grandson of Henry first earl of Manchester, was created by king William the third 1700 lord Halifax, and by king George the first viscount Sunbury and earl of Halifax, which titles became extinct upon the death of George, third earl of Halifax, 8 June 1771.
Margaret, daughter of Thomas earl of Coningsby, and wife of sir Michael Newton knight of the Bath, was created by king George the fist 1716 baroness and viscountess Coningsby, and succeeded to the title of countess of Coningsby upon the death of her father 1729.