A companion piece to the William Wickham book is this article by the same author. (not sure if this info is included in the Wickham book, since I've not had a chance to read it yet)
The British Secret Service and the Escape of Sir Sidney Smith from Paris in 1798 by Michael Durey.
This article makes it clear that the stories published immediately after Smith's escape from Paris cannot be counted on. Clearly, much of what was written was sourced from Smith who had, out of necessity, to produce cover stories to protect his spies and agents in France. This included when Smith was captured in Le Havre, since Smith was almost certainly conducting, or had just finished, an undercover operation at the time he was caught.