Born on 4 June 1845 at Wymondham, Norfolk and educated at King Edward VI's Grammar School there. At 15 he was apprenticed to Robert Sayle (1816-1883), a Cambridge retailer, under whose influence he became a Wesleyan and joined a group of preachers that led to the building of Hills Road WM, Cambridge. A draper by trade. on leaving Cambridge for London he joined Hinde Street WM and then entered into business at Bedford, before moving to King's Lynn because of his wife's health. In 1877 he acquired the town's drapery business of John Thornley and in 1890 C.W Perry joined him in partnership. The business became Jermyn and Sons Ltd In 1927 and was bought by Debenham's in 1942.
He was a local preacher and a class leader at Tower Street chapel for over forty years. In the 1880s he was circuit steward of the King's Lynn WM Circuit He was a District representative to the WM Conference on several occasions and was greatly interested in the temperance movement. He was associated with the founding of Culford School.
He was much involved in public life. He was a councillor and alderman for more than twenty years and mayor in 1897-8. He also served on the Norfolk County Council for fifteen years and was a JP. He was particularly concerned with the creation of small holdings, being Secretary of the Norfolk Small Holdings Association. He was knighted in 1919 and died on 27 June 1921.
His grand-daughter Enid Jermyn and an older sister were missionaries in India, serving in Hyderabad and Medak 1941-1964.