After preaching in the Fylde country (between the Lune and the Ribble) he was presented in 1656 to the vicarage of Walton-on-the-Hill, Lancashire, a parish which then included the town of Liverpool.
Both at Warrington and Manchester he attended the ordinary services of the Church of England, preaching only occasionally on Sunday evenings in his own dwelling to such restricted gatherings as the law allowed.
The Toleration Act (1689) called attention to the insecurity of his position: Birch Chapel, being a consecrated place, could not be licensed as a dissenting meeting-house.
Finch was a member of the provincial meeting of united ministers (presbyterian and congregational) formed in Lancashire in 1693 on the basis of the London 'agreement' of 1691, involving a doctrinal subscription.
In 1691 he was invited to become colleague at Norwich to Josiah Chorley; his first entry in the presbyterian register of baptisms is dated 1 June 1692.
He remained at his post for over sixty-two years, and survived Edward Crane and Thomas Dixon the younger, both of whom had been designated as his successor.
Himself a strict Calvinist, he contributed much, by his love of peace, to preserve concord when doctrinal differences threatened to divide his flock.