It's a Library Thing...
Someone's just pointed me in the direction of www.librarything.com, which is a fascinating website that allows you to catalogue your books online.
A search on Leslie Charteris shows that 67 users own 441 books by Charteris, which is an average of 6.5 books per user.
It seems that the most popular title is The Saint in New York with The Saint: Good as Gold (one of those pesky American only anthologies) bringing up the rear.
There's a loads more interesting stats you can find off this site--I suspect you to have to keep in mind that this is a cross-section of users who've taken the time to enter their collection details on the web--but what made me smile was "16 members have the book in their library. There are 44,729 books more popular."
44 729 books more popular? How can that be?!!!