Jennings was the fifteenth child of Philip Jennings of Duddleston Hall, Shropshire and his wife Christian Eyton, daughter of Sir Gerard Eyton of Eyton, Shropshire.[1] He was descended from a Shropshire family which had suffered for its adherence to the Royalist cause during the English Civil War. He married Alice Breton.[1]
Naval career
Jennings was appointed a lieutenant on HMS Pearl in 1687, and served with the same rank in HMS St David and HMS Swallow, before being promoted to the command of the St Paul, a fireship.[2] In 1690 he was made captain of the newly launched HMS Experiment, of 32 guns, and employed in cruising off the coast of Ireland, where he intercepted a number of small vessels which were being used as transports by James II's forces.[3] In 1693, Jennings was nominated captain of the Victory, flagship of Sir John Ashby; later the same year he was transferred to the 62-gun HMS Mary, in which he went to the Mediterranean with Admiral Russell.[3] In 1696, he was removed to the Chichester, of 80 guns; and, in the following year, was entrusted with the command of the Plymouth, with which he captured a St Malo privateer.[2] Shortly afterwards, together with the frigate HMS Rye, he fell in with three French ships: one quickly surrendered, and Jennings, leaving the Rye to look after their prize, pursued the other two and succeeded in compelling one to strike her flag after a vigorous defence. Having conducted their prizes to port, the Rye and the Plymouth fell in with the Severn, a British man-of-war, and the three ships steered together for the coast of France, where they took five vessels laden with wine from Bordeaux, and a small ship of war.[4]
At the 1705 English general election, Jennings was returned as Whig Member of Parliament for Queenborough. He was absent from the division on the choice of Speaker on 25 October 1705 and was absent on active service until the winter of 1707–8. Then in November he gave evidence to the Lords on the encouragement of trade in the West Indies and in January 1708 gave evidence on the bill for the encouragement of seamen. He also submitted a paper containing thirteen proposals to improve methods of manning the fleet, of which three were included in a Lords address to the Queen. He was returned again for Queenborough at the 1708 British general election. In parliament, he supported the naturalization of the Palatines in 1709 and voted for the impeachment of Dr Sacheverell in 1710. At the 1710 British general election, he was defeated at Queenborough, but was returned in the poll as MP for Portsmouth. However he was unseated on petition on 3 February 1711.[1]
He was also appointed governor of Greenwich Hospital and Ranger of Greenwich Park from 1720, and presented the marble statue of George II by Rysbrack which stands in the Grand Square of the hospital.[2] in September 1721, he was advanced to Senior Naval Lord[8] Also in 1721, he acquired Newsells Bury at Barkway in Hertfordshire.[3][9] He was becoming deaf, but resigned from the Admiralty Board in June 1727 because he objected to serving under Lord Berkeley, the first Sea lord. He was returned again as MP for Rochester at the 1727 British general election. Although Berkeley was dismissed from the Admiralty board in 1727, Jennings was not keen to return, hoping instead for a promotion or peerage. He was promoted to rear-admiral of England in January 1733, but resigned a year later when Sir John Norris was made admiral of the fleet and commander in chief.[10]