I have an old property 1892 with English garden wall bond brick work, the outside is rendered and masonary painted. Inside I have damp from 43 inches upwards for about two foot then the wall is dry again, I have removed blown plaster revealing brick work, at each row of headers a tape can be inserted 8 inches. Below 43 inches the wall appears to be covered in concrete prior to a layer of plaster, this part of the wall does not appear damp, so I have not removed it.
Any advise on how to treat the damp, and is the concrete a form of damp proofing?