Not really a Flashman novel, but it does feature Harry Flashman as a major character, and uses the same technique of conveying the feel of a historically-interesting context — in this case, England just before the outbreak of the First World War — through the exploits of an only-just-fictional character. And Mark Franklin is definitely not Flashman, which makes a refreshing change.
I do miss the footnotes, though! Their lack makes it less obvious which details are fictional and which aren't — although that did give me an excuse to go away and read about the events it's talking about in more detail, and perhaps that was the intent. Highly recommended.