One day, I killed time at a bookstore while waiting for a friend and my eyes were caught with the words 'London Bridge', 'Strand', 'Westminster' and the images of London maps on book covers. I had no idea who Susanna Gregory was at that time. Therefore, I read the summary on the back cover and remembered the name 'Susanna Gregory' in which I can check at home later.
After reading more about the author and her 'Thomas Chaloner Mystery', I decided to search my books-trove, Abebooks.com, and finally got 5 books in US$30.29.
When I flipped to the end and see 'Historical Note' which states that one of the character Robert Leybourn was a person in reality:
'William and Robert Leybourn were booksellers, whose shop was in Monkwell Street in Cripplegate. In the late 1660s, William was the surveyor employed to work on Ogilvy and Morgan's famous port-Fire map of London, now republished as The A-Z of Restoration London.' (pp.501-502, A Conspiracy of Violence, 2007)
Robert Leybourn seemed not as well known as his brother William and seemed to disappear from the second book Blood on the Strand and William played a comparatively important part from the third book The Butcher of Smithfield. There are not much information about William's life but an engraving dated year 1650 sold in Christie's auction on 22nd May 1996 in New York (Sale: 7873, Lot: 212). Other 'Historical Note' on the second book Blood on the Strand about William:
'William Leybourn was a mathematician-surveyor who drew maps of London after the Great Fire of 1666'. (p.455)
Gregory's 'Thomas Chaloner' series are about 17th Century's London and she mentioned many significant places where the main character Thomas Chaloner appeared and crime scenes happened.
It will be my second project to track down those places with comparing with the A-Z of Restoration London and modern maps.
Ogilby and Morgan's large scale map of the city as rebuilt by 1676 at British History Online