The answer? Fifteen days, twenty hours and fifty five minutes.
I know that because I finished Dream Paris yesterday and I've been clocking the time I spent working on the novel.
The time includes the writing of the first draft of the novel and three redrafts: first redraft, the second following feedback from my wife and a third following feedback from other readers. The novel is now with my editor awaiting his feedback and will probably undergo at least two further redrafts.
I've not counted time spent planning the novel or the notes I made prior to embarking on the writing. As some of the ideas, scenes and dialog that appear in the novel have been collected over several years, it was difficult to measure this.
Some statistics you might find interesting:
I started on the 18th February, 2014 at 9:58am
I finished on the 20th February, 2015 at 3:00pm exactly
If I'd been writing an 8 hour day the novel would have taken around 48 days to complete.
The book is almost exactly 100 000 words as it stands, given that it took just short of 381 hours to write that gives an average word rate of a rather pitiful 262 words an hour. Given that the first draft took around half the total time to complete, that makes the word rate a more respectable 524 words an hour. As I normally average around 850 words an hour, the missing words are partially accounted for by the fact that I cut around 60 000 words from the novel due to mistakes, changing my mind or no good reason.
If you're interested how I collected this data, well, have I mentioned Emacs? I recorded the time taken using org-mode. You can find out more by reading this post on My Emacs Writing Setup.