He was born on 8 February 1754 at Barnack in Northamptonshire, where his father, Thomas Rennell (1720–1798), a prebendary of Winchester, was rector. In 1766 Thomas was sent to Eton, and thence proceeded to King's College, Cambridge, where in due time he became a fellow. He was a diligent student, and though, as a King's man, he could not compete for mathematical honours, he obtained in 1778 one of the member's prizes for bachelors for the best Latin essay on 'Government'. He graduated Bachelor of Arts (BA) in 1777, Master of Arts (MA) per lit. reg. in 1779, and Doctor of Divinity (DD) in 1794.
At Cambridge he made the acquaintance of Thomas James Mathias, and contributed to the notes of his Pursuits of Literature (1794-7). Mathias mentions him in the poem, in conjunction with Bishops Horsley and Douglas. Rennell left Cambridge on taking holy orders, and became curate to his father at Barnack. His ample leisure he devoted to theology. His father soon resigned his prebendal stall at Winchester in his favour, and in 1787 he undertook the charge of the populous parish of Alton. Subsequently, perhaps through the influence of the Marquis of Buckingham, he was presented to the rectory of St. Magnus, London Bridge. When he proceeded D.D. at Cambridge, in 1794, he preached a commencement sermon on the French Revolution which impressed Pitt, who called him 'the Demosthenes of the pulpit'. In 1797 Pitt urged him to accept the mastership of the Temple. He resigned his prebendal stall next year, and devoted himself to his new office. He made friends with the great lawyers of the day, such as Eldon, Stowell, Kenyon, and Erskine, and cultivated the society of the junior members of the bar and the law students. Again, through Pitt's influence, he was appointed in 1805 dean of Winchester, and extensive repairs took place in the fabric of the cathedral under his direction.
Death and legacy
In consequence of growing infirmities, heightened probably by the premature death of his only son, he resigned the mastership of the Temple in 1827, when he wrote a touching letter of farewell to the Inns of the Inner and Middle Temple. He died at the deanery, Winchester, on 31 March 1840, in his eighty-seventh year. In 1786 he married at Winchester Sarah, eldest daughter of Sir William Blackstone, the judge, by whom he had an only son, Thomas (1787–1824)
Rennell's reputation stood high as a scholar and theologian. He was long an intimate friend of Henry Handley Norris and the rest of the high-churchmen who formed what was called the Hackney phalanx or "Clapton sect". Dr Samuel Parr described him as 'most illustrious'.
He printed nothing except a volume of sermons Discourses on various Subjects (1801), most of which had been previously printed separately. They are scholarly productions, and the writer shows erudition in the notes.
- "Rennell, Thomas (RNL773T)". A Cambridge Alumni Database. University of Cambridge.