Blitzed — Robert Swindells

George is fascinated by World War Two. Bombers, Nazis, doodlebugs. But he discovers the reality is very different from how he had imagined it when a school trip to a World War Two museum leads to a timeslip - and George is in London at the time of the Blitz! He joins up with a group of other homeless children, struggling to survive. And then they suspect someone they know of being a German spy...