[Closed] Any damp experts in the house?

Just moved into a new house (if 100 years old is new), upon stripping wallpaper we've noticed damp patches at the same point on all 3 chimney breasts (just where the chimney breast meets the ceiling, and no doubt beyond into the loft space). At a quick glance, the flashings/stack etc look ok so I'm guessing the damp is caused by condensation (the fireplaces have been closed up). We want to open up the fireplaces again anyway - is this likely to remedy the problem or do we need to do anything else?

TIA 🙂