Evangelical incumbent of Haworth, Yorks, he was described by Frank Baker as 'the first beneficed clergyman in northern England to exercise an unrestrainedly evangelical ministry' and 'the commander-in-chief of revival in the north'. Born at Brindle, near Preston, on 3 September 1708, he graduated from Christ's College, Cambridge in 1730 and was ordained priest in 1732. After curacies at Littleborough and Todmorden, he moved to Haworth as perpetual curate in 1742. He was hostile to Methodist preaching until he came under the influence of William Darney in 1744, provoking the gibe, 'Mad Grimshaw is turned Scotch Will's clerk.' He received first Charles and then John Wesley at Haworth, forging a firm friendship with them, though adopting a moderate form of Calvinism. They entrusted him with the superintendency of an extensive preaching circuit known as the Great Haworth Round, encompassing parts of North and West Yorks, Lancs and Cumbria. He was the only Anglican incumbent to act as secretary of a Methodist quarterly meeting held near Todmorden in 1748.
Grimshaw reported to the Archbishop of York in 1749 that during his incumbency summer communicants at Haworth had increased from a mere dozen to some 1,200. By then John Wesley was ready to name him as successor to himself and his brother, but in the event Grimshaw died on 7 April 1763 from a fever caught while visiting a sick parishioner. His genuine pastoral concern and deep spirituality have often been obscured by the caricature of the over-zealous cleric, horsewhipping backsliders into worship, most grotesquely by Glyn Hughes in his novel Where I used to play on the Green (1982). His behaviour and 'language of the market place' were certainly robust, but as John Wesley wrote: 'A few such as him would make a nation tremble ... he carries fire wherever he goes.' Charles Wesley described him as 'my right hand, my brother and bosom friend'.
Grimshaw's parsonage 'Sowdens' is located some distance away from the parsonage occupied later by the Bronte family adjacent to the parish church.
A number of his manuscript sermons survived and are at the John Rylands University Library, Manchester. A selection of these was published in 2008. His favourite text, 'To us to live is Christ, to die is gain' was inscribed on the chapel he built for the Haworth Methodists in 1758, with the help of a legacy from Mrs Mercy Thornton of Leeds..(The chapel was replaced in 1846 and its successor, in a dilapidated state after World War II, also had to be demolished. An inscription from the original chapel is incorporated in the wall of the 1830s' Sunday School. )