Kelly mentions B. W. Newton several times - not only in his private letters but also in printed book, pamphlets and his Magazine (The Bible Treasury). It is not enough to search for “Newton” because Kelly often used “B. W. N.” or “Mr. N.”. In other cases he does not name B. W. Newton explicitly but obviously referred to him.
Example: In the Article “the rapture of the saints: who suggested it, or rather on what scripture?” (in The Bible Treasury, New Series, vol. 4, p. 314-318, also published by T. Weston 1903) mentions - “Newton” 2 times - “B. W. N.” 5 times - “Mr. N.” 7 times.
1890 and later Kelly showed several times that some of the new teachings of F. E. Raven were as bad (or even worse) than those of B. W. Newton.