I first had the idea for the story in 2004. I saw a pair of documentaries on Channel 4 about the Plague of 1665 and the Great Fire of the following year. One of the talking-head historians made a comment about how the wealthiest people in London fled the city for their country estates as the fire spread, and that they left plenty of valuables behind to burn. The idea for the book occurred to me instantly. London's richest were so wealthy they could afford to lose those precious things, but to London's poorest, it might seem like a splendid opportunity. The title came to me instantly too.
The book went through several drafts. I originally envisaged the characters of Uncle Jack and Father Stephen being the same person, with the priest being the villain of the story. That idea didn't last long. In the first draft Uncle Jack actually was Samuel's uncle, and it wasn't until I changed my mind that the story really came together in the second draft - many a good book is made by a good baddie, after all. I kept the name Uncle Jack, though.
The character of Catherine was originally going to be a boy and the character of Gideon was originally going to be a girl, but it felt a bit old fashioned to have two boys saving a girl. Meanwhile the character of Wilf didn't appear until the final rewrite. Through every version, however, the character of Samuel remained the same, and he made the exact same decisions as he does in the version that has been published.
The Thieves of Pudding Lane