Mould on internal wall - possible penetration dampness?

[Skipsteer]

We've recently found patches of mould on the living room wall. One patch low down in particular (in photo). But mostly isolated spots across just the one section of wall (the one with the outside wall).

There's also some marks around the mains socket, which doesn't look like mould, but possibly damp.

The living room doesn't have especially large amounts of obvious condensation, although the 4 us spend most of our time in there.

I'm wondering if this might be penetration damp from the outside wall, possibly something to do with the old gas fire extractor unit attached to the outside wall. This has rusted quite a bit.

I wonder if we should remove it (as no longer have the gas fire), although worried that it might cause more damage if we try to remove it.

Just wondering if anyone has seen anything like this, especially the marks around the socket and can recommend possible solutions?

We have treated the mould and are thinking of painting the walls with Ronseal anti mould paint.

Just wondering if that's the right thing to do longer term?

Any advice or suggestions would be appreciated.

Thanks

 

[foxhole]

The unit may be letting in rain as it would have vented thru inner and outer wall , needs removing. Mould reflects a lack of adequate ventilation.

 

[Skipsteer]

Thanks for the reply.
Should it be quite a straight forward job to remove and seal up any gaps left by the exterior unit?
Is it likely to require any electrical work to secure and make the area safe?
Thanks

 

[foxhole]

Depends , it should have been isolated when disconnected. Filling hole should not be a problem.