He gained a reputation as an outspoken enemy of the local Roman Catholic inhabitants, who were in the majority.

His sermons on the dangers of popery also brought him wider attention, and in 1717 he was nominated as the warden of Manchester collegiate church; however, Francis Gastrell, as Bishop of Chester, refused to sanction the appointment on the basis that Peploe's Lambeth degree of Bachelor of Divinity was not a valid qualification.

[1] For that reason he returned to Jesus College and obtained his Bachelor of Divinity degree on 10 March 1718.

Gastrell died in 1725 and Peploe, supported by Edmund Gibson (Bishop of London) and the Duke of Newcastle, was appointed.

He was consecrated on 12 April 1726 and allowed to continue to hold his Manchester wardenship (which he held until he made way for his son in 1738), although he had to resign his position in Preston.