Family and Education

b. ?1713, 3rd s. of Sir Roger Mostyn, 3rd Bt., and bro. of John and Sir Thomas Mostyn, 4th Bt.  educ. Westminster June 1725, aged 11.  unm.

Offices Held

Lt. R.N. 1734; cdr. 1739; capt. 1740; comptroller of the navy Mar. 1749-Feb. 1755; r.-adm. 1755; ld. of Admiralty Apr.-July 1757; v.-adm. 1757.

Biography

Mostyn was court martialled at his own request in 1745, after allegations that he had failed to engage two French vessels off Ushant, and was acquitted. He sat for Weobley on the interest of Lord Weymouth, but his main political connexion seems to have been with his cousin, Lord Winchilsea. He supported Administration.

When Edward Boscawen sailed for America in April 1755 in command of a squadron, he appointed Mostyn his second-in-command, believing him to have been unfairly criticized.1 But a letter of 22 Oct. 1756 from Frances Boscawen to her husband hints at other reasons for Mostyn’s unpopularity: ‘I am very sorry for Mostyn. How deceitful are appearances! Would not one think him the pleasantest man in the world to live with?’, and she went on to contrast the respect Boscawen had from his men. Mostyn’s appointment as a junior lord of the Admiralty was the result of his friendship with Winchilsea.  He died 16 Sept. 1757.

Ref Volumes: 1754-1790

Author: Sir Lewis Namier

Notes

• 1. C. Aspinall-Oglander, Admiral’s Wife, 29-30, 39, 58, 218.