I am having a damp problem in my mid terraced house. The affected area is visible on the inside left hand corner of the house. The water staining seems to be in the left hand corner of the upstairs bedroom (see images B) and the living room underneath, again in the left hand corner......(see images A)

Both rooms share the affected wall with the house next door, which has neither a bathroom or kitchen against my affected rooms. I have experienced problems on this wall before and have had the gutter replaced, a new downspout and more recently a sleeve replaced between my gutter and next doors and silicone sealed. I thought that water was getting between the cavity, but i am assured that this cannot be the case now... I have included some photos if anybody could possibly suggest a solution I'd be so very grateful. Thank you in advance.