Hello, I have black spots of what looks like mould on my bedroom walls, but it is dry not damp, how can i get rid of it? any answers please!! penny  

.....and to get rid of it, Polycell make a mould killer.  This mould problem is not uncommon this time of year when the inside of a house is warm but external walls can be cold (especially if poorly insulated against the outside).  The warm moist air carries lots of water vapour (from breathing, cooking, showering etc) but when that warm moist air touches a cold surface it cannot hold the high level of moisture any more.  The moisture then condenses onto the cold surface.

This cold surface is now damp and possibly actually wet.

Over time this is the perfect breeding ground for mould and mildew.

Heat, insulation and ventilation are the answer.  Mechanical ventilation (extractor fans) for kitchens, utility rooms and bathrooms is essential.  Passive ventilation (trickle vents etc) also help.