Back in 2017/18 and totally missed by me and, I suspect, a good many others, this book on the John Wilkes London gunmaking firm was self-published: "John Wilkes Gun & Rifle Manufacturer A Family History" by Stephen Grist. As Stephen mentions in his preface, he came to realise that the number of folk who would be interested in reading about the Wilkes gunmaking dynasty would be remarkably few.
From my own experience I also know how difficult and expensive it can be to have a book that you have slaved over for many years get accepted by a publisher for production and distribution. Thus Stephen has only been able to publish his remarkably informative, well researched and extensive fascinating history of Wilkes by publishing it via Google, free to all. It means that unfortunately one is unable to add the book on one's bookshelves alongside established authors such as Diggory, Baker, Dallas, Masters, Tate et al, instead having to access it via computer, tablet or 'phone. A shame, as there are many fine photos and interesting images to ponder over whilst reading the engaging text.
Here is a link to it, which I found on the Craig Whitsey website: chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://www.craigwhitseygunmakers.co.uk/John_Wilkes_Gun___Rifle_Manufacturer_March_2023.pdf Craig used to work for the Wilkes brothers at their iconic Beak Street workshop before it closed.
Despite my own surname being Wilkes I am not related to the gunmaking Wilkes', but have long maintained an interest in the firm for obvious reasons. I was therefore delighted to come across Stephen's book purely by chance the other day and feel it deserves a much wider audience. I commend it to you if you are interested in fine London gunmaking.
Tim