Bomber by Len Deighton (1978)

Definately not a forgotten book, but sadly out of print. A real hard hitting novel of the life and death of ordinary people, German and British, caught up in an RAF bombing raid. Capturing a single day in 1943 the novel begins with the planning of the bombing raid, switching periodically from the young, apprehensive bomber crews to the ordinary townsfolk of a small town in Germany, and concludes after the bombing, giving a small and shattering account of those who have survived.
Also worth mentioning is the equally powerful 3 hour radio broadcast 'Bomber', based on the novel and was aired in 1995.

Tramp in Armour by Colin Forbes (1971)

Written by the master of suspense himself, 'Tramp in Armour' is one of the author's best novels that tells the exciting and often brutal story of a British tank crew trapped behind enemy lines, and their desperate attempt to reach the French coast. Along the way they encounter an array of corageous French locals, bloody skirmishes and the ocassional dive bombing. The book really climaxes in the final 50 pages, and for fans of Sven Hassel and real boys own adventure, this is for you.

Easter Day, 1941 by G.F. Borden (1987)

Written by an American rather than British, focused on a small band of British soldiers led by a battle hardened American, a vetreran of the Spanish Civil War, 'Easter Day, 1941' traces the story of these men in their captured Italian tank as they attempt to reach Tobruk, trapped behind enemy lines. A really tense and exciting book, well paced and, though not for everybody, has a lot more to it than your average ww2 thriller.

The Killing Ground by Elleston Trevor (1956)

Long out of print but another classic of men at war, and another novel focusing on the men of an armoured unit, 'The Killing Ground' follows the fortunes of a small group of men from the Normandy Landings through to its bloody finale in the Falaise Gap. The novel stands nearly 400 pages, and recieved huge acclaim during its release. A classic of men at war from the author of 'The Flight of the Phoenix', and a former flight engineer in the RAF who saw active service with Bomber Command during world war 2.

The Siege, a story from Kohima by Arthur Campbell (1956)

A sadly forgotten yet remarkable and touching book of the battle of Kohima. This novel is based very closely on fact, and was the first book of any kind to document one of most barbaric and bestial sieges involving British soldiers in history. Documenting a number of characters and their encounters, including one such character named as 'The Man in the Hole', 'The Siege, a story from Kohima' is one of the most touching and insightful books to have come out of the war.