There is another book on the Defiant under development and the author has set up a facebook page.
" 'The Defiant. By Day, By Night', a book covering the history of the Boulton Paul Defiant to be published by Frontline / Pen & Sword in 2020.
The manuscript will include the development of the type, the politics that went on behind the scenes, and the operational history. There will be a section on all Defiant combat claims, and a roll of honour to those lost on type; the latter will, where possible, have as many photographs of those aircrew."
https://www.facebook.com/Defianthistory/