A Prisoner of Dartmoor

A WWII novel about an young boy with asthma who wakes up in the countryside without knowing why. Each time he takes his inhaler to evade an attack, he loses his memory of what happened around that time. This story is a 1st person diary with dated entries. His diary helps him remember all the other things he never could, on his journey to be reunited with his parents.

I need to research World War II to be able to write this novel.