i agree with teabag.
mould can be cause by any of three things
1. inadequate ventilation
2. excessive condensation
3. rising damp.
Its easy to see if its caused by rising damp because it will occur mostly on low level. as there is mould on clothes in a wardrobe id say its an amalgamation of both inadequate ventilation and excessive condensation.
1. you need to ventilate
as this is a renovation the easiest way is to ventilate from the ceiling to the outside. do this in all rooms
2. you need to take down the existing studwork. you need to incorporate a breathable vapour membrane (tyvik) to the external of the studs and insulate between the studs with rockwool battens. Then reslab and skim.
3. upgrade the ceiling insulation by laying another 200mm of rockwool over the aeroboard.
4. dont assume the floor is fine. if you are doing remedial work, drill a hole in the floor and check the make up. if theres no insulation or polythene, and if you can afford it, take up the floors and incorporate insulation and polythene (DPM).