The Bare Bum Gang and the Valley of Doom by Anthony McGowan
Ludo, Noah, Jamie, Phillip and Jennifer are THE BARE BUM GANG! They have an embarrassing name but a cool Gang Den, so things could be worse.
Ludo leads the Bare Bum Gang on a raid through the Valley of Doom, deep in enemy territory. But as they are approaching their target, the BBG are ambushed by the Dockery gang. It looks like they are about to be annihilated (or pelted with mud really hard), but then they are rescued by a strange boy called Alfie. When they get back to their den, they find that their sweet stash has been plundered. The wrappers turn up in Ludo's binocular case. Added to the military fiasco in the Valley of Doom, the sweet theft is the final straw. Can Ludo keep his position as leader of the Bare Bum Gang? Or will he have to resort to desperate measures?