Thomas was succeeded by his eldest son William Cecil, the second Earl. He served as Lord Lieutenant of Northamptonshire. Lord Exeter married as his first wife Elizabeth, 16th Baroness de Ros. Their son William succeeded his mother in the barony at the age of one. However, he died childless during his father's lifetime (when the barony was inherited by his cousin Francis Manners, 6th Earl of Rutland). Lord Exeter had no other sons and was succeeded by his nephew, the third Earl. He was the son of the Hon. Sir Richard Cecil, second son of the first Earl. He represented Peterborough in the Short Parliament. His son, the fourth Earl, was Lord Lieutenant of Northamptonshire. He was succeeded by his son, the fifth Earl. He sat as Member of Parliament for Northamptonshire.