By Harald Penrose, published by Putnam & Co. 1969
I bought a copy of this book in a charity shop, a few weeks ago for just £2. It's a very interesting read and gives an insight into the design and supply side of WW1 British aircraft. There are lots of types that I had never heard of before (probably because they never saw combat, or went into production) and that I have certainly never seen modelled. It has 620 pages and lots of small photos.
I looked online and there are quite a few copies for sale but none under £40, so I definitely got a bargain!