I really enjoyed the first book in this series, Zulu Hart. Hart of Empire is even better. The central character, George Hart, is a young, 19 year old soldier. Having proved himself in South Africa, Hart is sent on a special mission to Afghanistan and we feel like we're on the journey with him.
Book and hero are akin to a Bernard Cornwell Sharpe novel- but the backdrop and the Great Game, public-school-hero flavour to book reminds the reader of a Flashman adventure.
Although Saul David is not quite in the league of Cornwell or Macdonald Fraser yet (but who is?) Hart of Empire is thoroughly enjoyable and engaging.