Late Britain is a Left 4 Dead 2 campaign which brings a British environment into play; rather than an American city or town filled to the brim with weapons, the survivors will find themselves using what they have in a world with almost no firearms at all.
The wooden wall is normally fully solid, and can be damaged by the infected team to show this hole, through which Boomers, Smokers and Spitters can attack through.
The wall may be completely broken once damaged, allowing an extra entrance/exit for other infected to attack through.