I recently acquired a copy of the 1851 "A Sketch of the Christian Experience, Call to Ministry, and Ministerial Labors of the Rev. John Peacock, Domestic Missionary," pubished by Tripp & Osgood, Concord, NH.
It includes a fairly detailed account of his activities from the 1830s to 1851. It includes the following information of genealogical interest:
father: William Peacock, Jr. (mother a baptist, name not given)