Weird circle on wall

[MikeL44]

Hi, I moved the sofa in my conservatory and found this strange circle on the wall. It’s about the size of a football. We were touching up the paint in advance of having some new flooring installed and this is AFTER we painted over it. I checked outside and nothing is leaning against the wall. Very strange.

Any ideas what this might be?

 

[MikeL44]

 

[securespark]

How long has the paint had to dry?

 

[tell80]

Is the wall Dot&Dab p/board?

 

[MikeL44]

It’s been about 12 hours, but the circle was there before attempting to paint over it.

 

[Koolpc]

Was there a vent / hole there in the past?

 

[JohnD]

Damp patch.

How old is the house?

How thick is the wall? About 9 inches plus plaster, or about 12 inches plus plaster?

Do you get condensation on the window?

Water may be penetrating around the window frame or at a damaged sill or render.

Photos of the outside please

 

[Mottie]

A hole where a floor mounted heater or A/C unit had been fitted in the past?

 

[conny]

A circle of cellophane that may have been over a previous tin of something, such as filler, and someone just slapped it against the wall till they had finished.