Rowley was a pro-Catholic Whig and well-connected country gentleman of Irish descent, whose family had returned Members for Downpatrick and Kinsale and produced five distinguished admirals. He had been kept waiting until 1812 to realize his ambition of representing Suffolk, where he commanded the yeomanry and had rebuilt Tendring Hall. As a silent but steady adherent of opposition, his votes generally cancelled out those of his colleague, the anti-Catholic Tory Sir Thomas Gooch, with whom he was returned ‘by the oligarchy’ for the third time at the 1820 general election.
He voted against Wilberforce’s compromise motion on Queen Caroline’s case, 22 June 1820, and came under considerable pressure, agitated by Bunbury and the Bury St. Edmunds reformers that autumn, to assist the extra-parliamentary campaign on her behalf. He eventually agreed (24 Dec. 1820) to present a contentious address to her from freeholders in Suffolk’s Lackford Hundred and he acted with her parliamentary partisans in 1821.
Rowley voted for Catholic relief, 6 Mar. 1827, 12 May 1828. He was obliged to deny reports that he had voted for the financial provisions for the duke of Clarence in February 1827.
Rowley’s eldest son William died without issue, 24 Oct. 1830, but the marriages of Joshua and Charles into the Moseley, Vanneck and Arcedeckne families perpetuated the family’s close ties with the Whig hierarchy in Suffolk. He died in October 1832 at Tendring Hall, recalled as ‘an undeviating supporter of the popular cause’, and was buried in the family vault at Stoke-by-Neyland.
