I have just read this new book about the Gray family’s organs and the Victorian firm of Gray & Davison that effectively took over from them after 1851. The central character in the book is Frederick Davison, partly because we now know so much more about him. For a general reader (including me) the evocation of the times in which the firm flourished is most attractive, and Nicholas writers so well that one forgets what a large book it is and how much source material has been handled. It is published by the academic publish Boydell and Brewer https://boydellandbrewer.com/organ-building-in-georgian-and-victorian-england.html
Not cheap, but for organ historians it will be a classic.