Ventilate and use Dettol Mould and Mildew regularly and you won't have an issue
Extractor and door open, my old place had REALLY bad mould, after bleaching and anti-mould spraying the walls it was only a week until it came back, why? Rather than cleaning it the landlord had painted over a mouldy wall so we had peeling paint to!
Are you living in my building? You don't live in Muswell Hill do you?!
My flat has a really bad mould problem as well. I spent last night and this lunchtime trying to get rid of it. I served notice and have agents coming round for viewings. I've got rid of most of it but not all. I found out that three of the eight flats in the building have served notice at the same time. The guy downstairs from me moved out specifically because of the mould - even a de-humidifier couldn't get rid of it.
It seems that the agents in my building just paint over the mould between new tenancies.
Corner of a bedroom after 3 months (cleaned by us spotlessly when we moved in:
Condensation mould they say, completely unrelated to the peeling paper and the pointing thats dropped out of the wall on the exterior of course...