The following is the entry for John Clavell in William O'Byrnes 1849 'Naval Biographical Dictionary'.
CLAVELL. (Captain., 1808. f-p., 33; h-p., 32.)John Clavell died 11 March, 1846, aged 70. This officer entered the Navy, 24 June, 1781, as Captain’s Servant, on board the Centurion 50, on the books of which ship, and of the Warwick, he was borne until Feb. 1783. He embarked, 11 Nov. 1792, as A.B., on board the Duke 90, Capt. John Knight; and while next employed, from Jan. 1793, to March, 1797, in the Victory 100, flag-ship, in succession, of Admirals Lord Hood, Robt. Mann, Robt. Linzee, and Sir John Jervis, served, as Midshipman, at the occupation of Toulon, on shore at the reduction of Bastia and Calvi, in Hotham’s action of 13 July, 1795, and in the battle off Cape St. Vincent, 14 Feb. 1797. He also, on one occasion, when in the Vicrory’s jolly-boat, with only 6 men, effected the capture of two transports laden with powder. On 21 April, 1797, Mr. Clavell removed from the Ville de Paris 110, flag-ship of Lord St. Vincent, to an Acting-Lieutenancy in the Excellent 74, Capt. Cuthbert Collingwood. Subsequently to his official promotion, which took place on 6 July in the same year, he joined, on the Home station, 27 Aug. 1798, and 8 Oct. 1800, the Marlborough 74, Capt. Thos. Sotheby, and Barfleur 98, Capts. Stevens and Irwin – and, between 31 May, 1803, and the autumn of 1805, as First-Lieutenant, the Venerable, Colossus, and Culloden 74’s, Prince 98, Venerable again, and Dreadnought 98, all flag-ships of Vice-Admiral Collingwood. Removing with the latter officer, on the date last mentioned, to the Royal Sovereign 100, he shared, and was wounded, in the battle of Trafalgar, and, for his conduct on that day, was promoted, by commission dated 22 Oct. 1805, to the command of the Weasel sloop of 18 guns. We subsequently find him capturing and driving on shore six transport-vessels, intercepting a trabaccolo with despatches, and performing a variety of effective services in the Adriatic. The 4th of Feb. 1808, was marked by Capt. Clavell’s promotion to Post-rank in the Glatton 50, lying at Palermo; soon after which he invalided home. His next appointments were, in the course of 1811, to the Royal George 100, Laurestinus 24, and Orlando 36 – which latter vessel he appears (part of the time as Flag-Captain to Sir Rich. King) to have commanded, off the Western Islands, in the Mediterranean, America, and China, and in most parts of India, until Feb. 1819, when he returned to England in the Malabar 74. He was afterwards employed – from 1825 to 1827, as Captain of the Ordinary at Portsmouth – from 4 July, 1835, until April, 1837, as Superintendent of the Packet Establishment at Falmouth, with his pendant on board the Astraea 6 – and, from the latter date until 1841, as Captain-Superintendent (in the Brune 22, and Poictiers 74) of Chatham Dockyard. He was appointed to Greenwich Hospital 22 Aug. 1841.
Capt. Clavell, who died Senior Captain of the Navy, and had received a pecuniary reward from the Patriotic Fund, was father-in-law of the late Lieut. Wm. Simpson Blount, R.N. (1824); and had also a daughter who married a son of Vice-Admiral Henry Garrett. His son, John, is a Commander, R.N. Agent – Joseph Woodhead.