Laws and sausages, we know, are better not seen in the making; and neither are ‘black ops’. Waterloo may have been won on the playing fields of Eton, and Trafalgar on the dunes near Burnham Thorpe, but Britain’s secret war against Napoleon was won in less wholesome places. ‘This is a book about propaganda, spying and covert operations… a very modern story of secret committees, slush funds, assassination,’ writes Tim Clayton, whose Waterloo: Four Days that Changed Europe’s Destiny was by far the most scholarly of the many volumes produced for the bicentenary.