These two marvellous books are advised on the British Badge Forum, and are a free download.
A huge work of scholarship.
DO NOT HESITATE!
I quote:
RAF Collectors Guide 2020The final version of my RAF books are now available, free of charge. Anyone who previously requested copies may like to have the latest update. I have written these books as the result of many years of collecting. There are two volumes one of 582 and one of 144 pages of RAF history in badges and emblems. The e-books are available to download here (Large! Not suitable for mobile phones): The link is available for the next 28 days.
https://we.tl/t-qxnHMIlpG4
I know these are trying times for many, and the books are free, but if you download it you may like to consider showing your appreciation for the work I have put into it by making a contribution using PayPal at the address shown in the books