Looking at the picture, it seems the wall has had a wardrobe or the like placed against it. I'm no expert but that will be breading ground for damp patches, the damp will have been caused by bad ventilation behind the furniture. The house I have recently purchased needed a new damp course throughout, one room had a large welsh dressser against a internal wall and it was the same as the picture, also seen it in other non mil houses.
Another scarey thought, the new patch they are building on the S***ton Road look very nice, but how many are going to be given up to social housing (10% plus). A new thread in a few years 'Can the Staish help sort out my noisy non service neighbours'