Post Script: When I see a cheaper copy (than £40 - Kindle could be an option) I will but this book (see below). I managed to flick through a reference library copy. It is a reassessment of the potential of the Fairey Battle. It claims it was more strategically/operationally mishandled rather than being an implicitly bad design.
Note: More successful designs had "two engines" - it seems that it was being asked to perform too much with too little horse power, with too big a crew (three)!