The following is the entry for William Edmonstone in William O'Byrnes 1849 'Naval Biographical Dictionary'.
EDMONSTONE. (Commander, 1841. f-p., 21; h-p., 4.)William Edmonstone, born 29 Jan. 1810, is eldest son of the late Sir Chas. Edmonstone, Bart., of Duntreath, co. Stirling, by his second wife, Louisa, daughter of Beaumont, second Lord Hotham, sister of the late Vice-Admiral Sir Henry Hotham, G.C.B., and niece of Admiral Lord Hotham. He is half-brother oi the present Sir Archibald Edmonstone, Bart.
This officer entered the Royal Naval College 5 Sept. 1822; and embarked, in Oct. 1823, as a Volunteer, on board the Sybille 48, Capt. Sam. John Pechell, whom he accompanied to the Mediterranean. On returning to that ship, after having been detached for some months into the Medina 20, Capt. Timothy Curtis, he appears to have been dangerously wounded in the face and arm, while employed in the boats, in a desperate action with some pirates, off the island of Candia, 18 June, 1826. Mr. Edmonstone, whom we next find joining the Columbine 18, Capt. Wm. Symonds, and subsequently proceeding to India with Lord Wm. Bentinck, the Governor-General, in the Undaunted 46, Capt. Augustus Wm. Jas. Clifford, obtained his first commission 23 Feb. 1829. He was afterwards appointed – 14 May, 1829, to the Seringapatam 46, Capt. Hon. Wm. Waldegrave, in South America – 7 June, 1832, 11 Feb. 1833, and 18 March, 1836, to the Belvidera 42, Alfred 50, and Vanguard 80, commanded on the Mediterranean station by Capts. Hon. Rich. Saunders Dundas, Robt. Maunsell, and Sir Thos. Fellowes – 30 April, 1839, to the Impregnable 104, flag-ship at Plymouth of Sir Graham Moore – and, 26 July, 1840, to the command, in the Mediterranean, of the Weasel 10. He acquired his present rank 23 Nov. 1841; and has been employed, since 6 April, 1844, as an Inspecting Commander in the Coast Guard.
Commander Edmonstone married, 13 July, 1841, Mary Elizabeth, eldest daughter of Lieut.-Col. T. W. Parsons, Resident of the Island of Zante.