The following is the entry for Stephen Grenville Fremantle in William O'Byrnes 1849 'Naval Biographical Dictionary'.
FREMANTLE. (Captain, 1842. f-p., 15; h-p., 9.)Stephen Grenville Fremantle, born 30 Aug. 1810, is youngest brother of Capt. Chas. Howe Fremantle, R.N. This officer entered the Royal Naval College 5 June, 1823; and embarked, 26 June, 1824, as Midshipman, on board the Seringapatam 46, Capt. Chas. Sotheby, on the Mediterranean station. Until hie promotion to the rank of Lieutenant, 25 Oct. 1829, he next served on board the Challenger 28, and Pallas 42, both commanded by Capt. Adolphus FitzClarence, Briton 42, Capt. Hon. Wm. Gordon, and Volage 28, Capt. Lord Colchester. He was afterwards appointed, on the South American, Home, and West India stations – 9 Aug. 1830, to the Clio 18, Capt. John Jas. Onslow – 13 Oct. 1831, to the Seringapatam 46, Capt. Hon. Wm. Waldegrave – 1 Nov. 1832, to the Comus 18, Capt. Wm. Price Hamilton – 17 Dec. 1832, to the Vernon 50, flag-ship of Sir Geo. Cockburn – in July and Aug. 1833, to the command of the Skipjack and Pincher schooners – and, 16 July, 1834, to the President 52, bearing also the flag of Sir G. Cockburn. Ascending the next step in his profession 22 Dec. 1836, Capt. Fremantle further joined, at the Cape of Good Hope – 24 May, 1839, the Clio 16 – 12 Aug. 1841, as Acting-Captain, the Southampton 50, flag-ship of Edw. Durnford King – and, 6 Nov. 1841, the Wanderer 16. He was elevated to the rank he now holds 26 Feb. 1842, but did not leave the Wanderer until 31 July, 1842, previously to which lie appears to have made a visit to China. Since 11 Jan. 1847 Capt. Fremantle has been in command of the Raleigh 50, bearing the broad pendant of Sir Thos. Herbert on the S.E. coast of America.
He successively officiated as Private Secretary, during Sir Robt. Peel’s administration, to the Secretary at War and the Chief Secretary for Ireland. Agents – Goode and Lawrence.