Damp patch

[Betdo]

I live in a simidetatched house on taking the wallpaper off in the front room , found a black mould .
Starting from ground floor about 2 feet high.Above up staires bedroom as well.
I have checked the loft wall, roof, outside guttering and downpipe .No sigh of damage etc.
Now a a loss to where to start.

 

[timbook]

Clean off any mould that you can with Bleach and a wire brush. Wear gloves and a mask so as not to breath it in or get it on your skin, although I doubt it'd harm you that much!
Once that is done, try a decent anti mould/anti damp type primer from Owatrol or Zinsser. Prime with one of these and then paint as normal.
A dehumidifier, even a disposable cheap one will prevent mould from forming again.
But if you can afford it, finding out the actual cause or reason for the mould will always be the best option. You can then cure it completely before proceeding.