While we were moving the old wardrobes out of the bedroom we found this
I cleaned it off and thankfully it's all come out, the paintwork is not bubbled and the wall is not damp or overly cold which is a good sign that it's just some mould from moisture in the flat or from not enough ventilation and not actual damp. I also let the landlord know as they had a damp proof coating done so if we start getting damp they might need to get that looked into. They provided us with a dehumidifier to use as in winter it's hard to open windows all the time which is very nice of them, but I ran a dehumidifier for 2 years at our last house (Literally it was on 24/7) and I'd rather not start all that again so I'm trying to open the window in the bedroom more often as to be honest we probably weren't ventilating it enough. If I can't open the window a few times a week I'll run the dehumidifier in there though just to make sure. Also we are going to keep the furniture away from the wall slightly to allow air to circulate.
Have any of you ever had problems with mould or damp? What do you do to keep it under control?