[1] His father, John Byrth (1757–1813), was born and raised a Quaker in Kilkenny, County Westmeath, Ireland.
In 1786 John Byrth married Mary Hobling, a Wesleyan Methodist from an old Cornish family, in Plymouth Dock.
[3] Due to lack of money to pay for further education, Thomas Byrth took an apprenticeship at a chemist and druggist company in Plymouth founded by William Cookworthy (1705–80), a Quaker and pioneer porcelain manufacturer.
[3] He was a moderate evangelical, and was opposed to the high Calvinist teachings of Robert Hawker (1753–1827) that were in vogue in Plymouth at the time.
[4] Byrth was active in the Plymouth Athenaeum, described as "the centre of all literary, scientific and artistic life in South Devon.
[6] One of his pupils was Benjamin Wills Newton, an extremely gifted boy from a Quaker background who followed Byrth when he moved to Diptford in the spring of 1823.
[1] On 5 February 1827 Byrth, then curate at St Clement's Church, Oxford, wrote that Henry Bulteel "has created a most powerful sensation here, by preaching ultra-Calvinism, and circulating Dr Hawker's tracts.
"[8] In 1827 Byrth was presented by Thomas Greenall to the small incumbency of Latchford, in the parish of Grappenhall in Cheshire.
[1] In 1833 John Hatchard, Vicar of St. Andrew, Plymouth, nominated Berth to the perpetual curacy of St. Paul's, Stonehouse.
[9] In 1834 Byrth was collated by John Sumner, Bishop of Chester, to the rectory of Wallasey, Cheshire, now part of Merseyside.
[1] A fellow-clergyman, G. R. Moncreiff, published Remains of Thomas Byrth, D.D., F.A.S., Rector of Wallasey, with a memoir of his life in 1851.