damp on upstairs walls not related to roof

Check the insulation in the loft!! if its on the ceiling it's nothing to do with external walls its ventilation and a cold clash on the spots its appearing.

Hi, The best thing to do is to get somebody on site to inspect the exterior render in that area, the interior of affected walls, the adjoining loft, check for chimneys in the vicinity and have a good look at the flashing there and last but not least check whether water pipes are present and check those for leaks in elbow joints etc. This should not take more than 1 hour. Once the cause is known, the best way of repairs should be selected and a written quote obtained for repair works. Bear in mind it could be a combination of several issues. It depends a lot on the type of building (era/ age), the construction methods used and any changes/ alterations that have been made to it.

I would put this down to humidity in the room and lack of ventilation, maybe look at installing a dri-master, or try using the window vents first and make sure there is no clutter on top of wardrobes etc

Yes air flow is main problem would have to see it to assess what you need is there airflow tiles in roof? Have windows got vents in ? Air bricks in walls? Is there clutter in rooms?

Not disagreeing with the other answer on this , but it could be felt issue lower roof also check insulation in loft no open areas and good ventilation in bedroom is this a new issue over the winter months .....

I agree. This is a result of condensation onto a cold surface. The loft insulation will help prevent the ceiling being cold. But ventilation will help. Most importantly is to use the extract fan in the bathroom and kitchen plus keeping the door shut when steam is being generated. If the kitchen fan is a cooker hood this should be vented to outside and not re-circulating. Finally the warmer the room, the less likely you are to experience condensation.