Henry Allen "Harry" Ironside (October 14, 1876-January 15, 1951) was a Canadian-American Bible teacher, preacher, theologian, pastor, and author.
Ironside was one of the most prolific Christian writers of the 20th Century and published more than eighty books and pamphlets, many of which are still in print. As an editorial reviewer wrote of a 2005 republication, "Ironside's commentaries are a standard and have stood the test of time."
This is probably the best history of "brethren" available. It's not as complete as Noel's as far as historical details, but it's much more complete in its analysis. There is some bias, of course. Ironside was with the so-called grant brethren, and occasionally that shows through in his comments. But really, he writes with sympathy for"brethren", even when he's pointing out some pretty terrible flaws.
His telling of the Ramsgate division is particularly excellent.