Where is the damp coming from? (Pictures)

A concrete floor without seeing it Regards Chris

The walls each side of a door like this are always much cooler than other parts due to their proximity to the colder doorway. They will in turn act as a ‘Dew point’ and will be attractive to airborne water vapour. It will settle on this areas over time and will absorb into the plaster. Eventually it will become wet and paint will peel. You need to either cut down your moisture production internally or move to a decent form of active ventilation. Passive ventilation is seldom enough for modern lifestyles.

There could be a few reasons why there is damp it could be lateral penetration coming up from the concrete floor or pointing or fillet outside could be cracked damaged or you physical damproof corse could be failing.