A Book of Sandhurst Wargames by the late Paddy Griffith was a completely unexpected find and a real bargain. The book starts with a history of wargaming that most gamers would find fascinating to read.
The rest of the book contains four sets of rules covering four periods of history. Each game is detailed with history and background and lots of useful illustrations. Unfortunately this copy is missing the game boards and tokens for play but its still and interesting read none-the-less.