Wall is shared with a neighbour, it's a terraced house, so double wall. Don't know what they have on their side of the wall, but can hear some strange noises just now.
Wall behind our fridge in the kitchen is slightly damp (goes up to about 2 metres high) and there is a mouldy smell in the area. Wall is shared with a neighbour and it's in the corner of the house. We skimmed and painted the wall almost 2 years ago when we moved in and knew about the problem but...