In 1748 Percival wrote two pamphlets in opposition to local High Church clergy: A Letter to the Reverend the Clergy of the Collegiate Church of Manchester, and Manchester Politics: a Dialogue between Mr. Trueblew and Mr. Whiglove.[1] He attacked in particular John Clayton, who had demonstrated Jacobite sympathies during the 1745 rebellion.[2] In this he was following up Josiah Owen and his Jacobite and Non-juring Principles freely Examined (1747).[3]
In 1758 Percival took part with some weavers in a dispute with their masters about wages. He published about his experiences A Letter to a Friend occasioned by the late Dispute betwixt the Check-Makers of Manchester and their Weavers; and the Check-Makers' Ill-usage of the Author, Halifax, 1759.[1]
Percival married Martha, daughter of Major Benjamin Gregge of Chamber Hall, Oldham. She died in 1760, aged 45. Their only child Katherine, married Joseph Pickford of Alt Hill, Lancashire. Pickford was later known as Sir Joseph Radcliffe, 1st Baronet, of Milnesbridge, Yorkshire, and it was to him that Percival's collection of manuscript pedigrees and other papers passed.[1]