I really enjoyed this book and all of Ms. Willis' Oxford Time Travel series. A very satisfactory ending that you could sorta, kinda guess, but still had surprises.
The night St Paul's was bombed during the blitz was very exciting - edge of your seat stuff - to use an overused metaphor.
As I've mentioned in previous reviews these books are as much a history lesson as they are sci-fi/time travel so don't let the sci-fi moniker dissuade you from trying one of these works.
Some reviewers mentioned it was difficult to keep up with the number of characters and their different places in time and location and names but I did not find it confusing or difficult at all.