Hi
My elderly parents have pointed out to me today that the dining room walls in their property are damp. I will post the pictures below and explain what is what.

This is the corner wall of the dining room - the wall to the left is an external wall - the one to the right is partly external and partly internal (see later photos of outside of property)

This is the wall that is partly external and partly internal. Has brown spots appearing - wall to the right on photo 1

This is around the window which is on the external wall (left on the first photo)

Same window as previous photo but top

This is the corner of the property from the outside - see photo 1

This is the wall that is partly external and partly internal - as you cane see there is a boiler outlet near the wall - could this cause the damp?? The brick wall is the neighbouring property, the white wall is my parents property
Hope this is clear if not please ask questions! Many thanks