Over the past few months I've noticed some very fine "spotting" of what I think is mould on a number of internal walls within the ground floor longe/dining room. The spots are very small and very fine in appearance but cover quite a reasonable area. I think they are creeping higher up the wall and at the worst spot have risen about 3 -4 feet above the ground.
The house is a mid terraced built in early 1900s. Is it a case of their not being enough ventilation in the room? Both the front and rear windows were painted shut when I moved in and haven't been opened for at least 5 years? The room gets some occassional air when front/back doors are open but this is not often particularly in winter.
Is this definitely mould and not damp? I can't see any tell tale "tide marks"?
Any further suggestions other than cleaning mould off and increasing ventilation? Should I be checking anything else?