Young Lions Feast

Sam, Alan, Alice and Aurora continue to fight against the German forces occupying England. The guerrillas sabotage SS plans to build a concentration camp and also prepare for L-Day: the Allied liberation of the Occupied South. The partisans take steps to deal with a traitor amongst their ranks.
Young Lions Feast is the sixth book in the Young Lions series and is a fast-paced, gritty novel set in an alternative history of the Second World War.
The Young Lions series:
Young Lions
Young Lions Roar
(winner of the NGP Publishing Prize 2012)
Young Lions Hunt
Young Lions Attack
Young Lions Prey