Leaking pipe?

[gk_adam]

Noticed some damp recently in one corner of a bedroom

Given the radiator outlet (and inlet) both go into the floor, my best guess is the radiator piping isn't the source of this. I'm quite certain also that there shouldn't be any other piping in that wall given it's inner wall, and no other radiators or bathrooms in either room next to this corner.

Any more investigation I could do myself before I call in the plumber?

 

[Wayners]

Corner of the roof. Water running down cavity?

What's outside?

Could also be the drain if you have one there

 

[terryplumb]

Is your heating system pressurised/ sealed ,if so are you experiencing pressure loss ?
Is property a bungalow ?
Are either of the walls external ?