These letters, in which Newton gives an account of his life, are a precursor to Newton's letters to Thomas Haweis, which were published as An Authentic Narrative Of Some Remarkable And Interesting Particulars In The Life Of John Newton (London, 1764). See reference to writing the letters to Fawcett in Newton's diary entry for October 25, 1762 (MA 731, f. 309), as well as other entries.
Beale is probably Thomas Beale (1733-1805), perpetual curate of Bengeworth and brother-in-law to Samuel Cooper. The two other individuals referred to may be Dr. John Coakley Lettsom and Dr. William Rowley (1742-1806).
Consisting of eight letters dated 15 October 1762 to 17 November 1762 addressed to Benjamin Fawcett, Presbyterian minister in Kidderminster, and copied out by Samuel Cooper, vicar of Loxley, Warwickshire. These are followed by extracts from letters in at least one later hand and signed Thomas Beale, J.C. Lettsome, and Dr. Rowley.