Damp on one side of internal wall

[hardcastlephil]

Evening all,

I've had a bit of damp smell in the lounge recently. I know I've got a leaking bay guttering and put it down to this, but on further inspection I've got some damp in the corner. It's behind a sideboard but all the plaster is blown with paint bubbling etc.

The thing is that the other side of the wall is completely dry. The other side is a more recent WC extension with concrete floors, so Im guessing that the wall in question was originally the outside wall. The lounge has suspended floors with boards.

There is a drain in the outside corner (and brick which needs re-pointing), but its about 3ft away from where the damp has appeared. I've tried to make a diagram:



My questions are:

Could the 'damp' just be poor circulation as all of this is behind the sideboard?
What are the most probable causes/solutions?

Any help much appreciated. If it helps it's a victorian house. It's had previous damp injection (about 10 years ago) but appears to be a rubbish job as it's halfway up the wall (well above joist height!).

Phil

[tonycane]

poor pointing or a gutter leak dripping in the corner would manifest itself as damp in that location.