Have lived in our house for around 3 years now, and this has got progressively worse every autumn/winter. Have had a couple people look at it, and they all say something different. Have topped up the sealant to the uPVC windows on the outside. House is semi detached, and around 100 years old. We have had loads of problem with damp on other walls, but think that is down to the outside wall needing repointing. Was hoping someone might recognise the patterns in the pics an know what it is! Have been told it's condensation... Any help much appreciated, so thanks in advance...