Murray had already been created Baron Mansfield, in the County of Nottingham, in the Peerage of Great Britain in 1756, with normal remainder to the heirs male of his body.

The 1776 earldom was created with remainder to Louisa Murray (née Cathcart), Lady Stormont (daughter of Charles Schaw Cathcart, 9th Lord Cathcart), second wife of his nephew David Murray, 7th Viscount of Stormont, while the 1792 earldom (referring to a fictitious Mansfield in Middlesex to differentiate it from the first earldom)[2] was created with remainder to his nephew Lord Stormont.

He was a Tory politician and served as a Lord of the Treasury from 1834 to 1835 in the first administration of Sir Robert Peel.

His son, the seventh and sixth Earl, represented Perth in the House of Commons and served as Lord Lieutenant of Perthshire.

[4][better source needed] In 1985, he married Sophia Mary Veronica Ashbrooke, and they had four children:[4] William David Murray and his heirs (as Earls of Mansfield, in the County of Nottingham) are identical to the Earls of Mansfield, in the County of Middlesex.