At the Firefly Gate by Linda Newbery
Henry never quite fits in. He feels like an outsider - and about to become even more so when his family move to the country and the prospect of a new secondary school looms. He retreats more and more into his shell, until he meets Dottie a frail old lady, but one with tremendous spirit. He feels as though he knows her, as though they have been friends for many years. And as she tells him about her wartime romance with an RAF navigator also called Henry, so our Henry is drawn into that world. In a series of mysterious, sometimes frightening events he re-enacts Henry's life...and learns that despite being dreadfully afraid, Henry acted heroically at the cost of his own life. Only our Henry knows the true story and it shows him a way through his own self doubts and misgivings.