I have black spot mould on the painted inside of an outside wall. It is inside a fitted cupboard which I had installed a couple of years ago - the cupboard has only doors and sides. The wall forms the back of the cupboard. The mould has been getting worse over time especially this year since Sept time. The clothes are loosely packed in an attempt to improve circulation and the clothes which I do not use every day smell fusty and some even have marks on them. The outside wall is rendered and painted on the outside but the paint is looking a bit grubby (not flaking). The damp course is below floor level. There is a soil pipe in the back of the cupboard but I have no particular reason to believe it is leaking. One suggestion is to put back a small radiator which used to be in the cupboard before it was enclosed. Do you think any other factors need addessing before or instead of putting the radiator back? I am concerned that the problem might not just be one of cold.