The book was first published in 1999. Clive Emsley (4 August 1944 – 5 October 2020) was a
British historian and criminologist.He wrote historical books including policing in England and France.
Clive Emsley has 63 books on Goodreads with 794 ratings. Clive Emsley’s most popular book is Great British Bobby.
www.goodreads.com
Mr AKA would have heard stories about horse accidents while working for the Gendarmerie. But he appears to be good at collecting snippets from books as well and IMO I'm sure he plagiarised a lot orally and in written form.