Gentlefolk,
A perusal of the various volumes provides a few data points:-
1: JCS Brough had a fretwork/handicrafts background, and a rather murky publishing history (which landed him in court, and paying damages). He acknowledges his authorship of the Fretwork volume, and I think we can safely assume he did not write any of the stuff in the other books, nor probably much in the magazine itself.
2: Some volumes have no Foreward and by nature are likely to be compilations
3: A couple of Forewards acknowledge multipe unamed authors.
4: The two volumes - Tools - Joints - are almost unique in listing Fairham as the author on the title page, suggesting he was a "real" person, of course that might not be his/her real name. Tools acknowledges an additional illustrator.
5: Fairham is acknowledged as the principal author of Carpentry
6: Wood Carving "... chapters have, for the most part, been written by an experienced woodcarver..."
7: Furniture Repairing... "most of the chapters have been written by Charles Taylor..."
8: Timbers for Woodwork was written by (and on title page) William Bullock
9: Household Repairs & Renovations, by JOHNSON. C. S
10: Practical Upholstery, by Ernest Boreham
So pretty specific attributions in those cases where there is a Foreward, and why use a pseudonym ?
By the way who nicked my copies of Staining & Polishing? This volume was a rework of earlier publications on the subject, and the 1st edition acknowledged no author, later editions indicated Fairham as the author (which does seem unlikely, perhaps he was the revisor).
So, not any closer to a Fairham bio, but I think he is likely to be an individual.