In 1723 he was elected, and in 1724 consecrated, to the see of St Davids. He was an active prelate, enforced the reading of the Athanasian creed, and is said to have learned the Welsh language sufficiently to be able to officiate in it. In a charge delivered in August 1728 he commended the treatise on the authority of Scripture by Faustus Socinus; with the result that this work was translated into English by an Anglican clergyman, Edward Coombe, and published in 1731 with a dedication to Queen Caroline of Ansbach.
In 1731 Smalbroke was translated to the diocese of Lichfield and Coventry. Two years later he contributed to the new buildings of Magdalen College. Samuel Pegge the elder accused him of filling the church at Lichfield with his relations. He died on 22 December 1749, and was buried in Lichfield Cathedral.
A portrait, painted by T. Murray, was engraved by George Vertue in 1733.
Works
Smalbrooke printed in 1706 a university sermon against the view of Henry Dodwell the elder that immortality is conferred by baptism. In 1711 he entered the lists against William Whiston, criticising (1714) Whiston's attempt to place the Clementine literature on a level with the New Testament, and treating (1720) the Arian worship of our Lord as an act of idolatry.
Thomas Woolston dedicated to Smalbroke his third Discourse (1728) on the miracles of Christ. Thus challenged, he published an elaborate examination of Woolston's argument. He began by applauding the prosecution of the author he was confuting; Daniel Waterland came in 1730 to his defence. He calculated the mercy which expelled six thousand demons ("legion") from one man, and sent only three apiece into "each hog". In passing he attacked the Quakers, whom Woolston admired.
His charge of 1735 spoke of "extraordinary local efforts to spread popery". In 1744 he charged against Methodists, anticipating George Lavington by his claim that "these new itinerants copy the popish pattern".
Besides sermons and charges, Smalbroke published:
Reflections on Mr. Whiston's Conduct, 1711, (anon.)
The New Arian Reproved: or a Vindication of some Reflections, 1711.
The Pretended Authority of the Clementine Constitutions confuted, 1714.
A Vindication of the Miracles of our Blessed Saviour, 1729–1731, 2 vols.; for Quaker criticisms of the second volume, see Joseph Smith's Bibliotheca Anti-Quakeriana, 1873, pp. 398 sq.
Some Account of … John Hough … Bishop of Worcester, 1743, (anon.)
Some Account of … Edmund Gibson … Bishop of London,’1749, (anon.)
His politics are attacked in Remarks on Two Charges … by a Friend to Truth and Liberty, 1738, signed at the end A Revolutional Tory, and ascribed (improbably) to Josiah Owen.
Select sermons:
The Reverence due to the House of God. A Sermon Preach'd in the Cathedral-church of Landaff, July 2d, 1721
Smalbroke married a sister of Richard Brooks, M.D., and left three sons and four daughters. The last of his descendants was his son Richard Smalbroke, D.C.L., of All Souls' College, Oxford, who died on 8 May 1805, aged 89, having been chancellor of the diocese of Lichfield and Coventry for sixty-four years. Thomas Smalbroke, a Socinian writer in 1687, was probably related to the bishop.