At the Firefly Gate (en Inglés) - Linda Newbery

Henry is not happy when his parents move from London to the village of Crickford St. Thomas. But he soon forms a friendship with an elderly neighbour, Dottie, and she starts to tell him stories about the Second World War and about another Henry who was a navigator in the RAF.

Then Henry sees a man standing at the garden gate, smoking a cigarette and surrounded by a cloud of fireflies. He appears to look straight at Henry - could he be the navigator? And what is the significance of the ghost's appearance?