Possible pipe leak from radiator

[Stef73]

I have discovered a wet patch on the carpet in my living room. Upon pulling back the carpet I find 2 stains, 1 is the wet patch I've just discovered and the other is dry. These are about a foot or so from the radiator in the room. I've tried drying it out. Also I turned the valve off at the radiator. Left it a little more to help drying then turned the radiator on again then the heating. It doesn't seem to be drying and is possibly getting wetter after turning on the heating.

Note: The floor in this room is concrete. It's an old terrace house.

There's no loss of pressure to the boiler whatsoever!

Help please.

 

[Madrab]

If it's no where near the rad pipe then it must be something else, that stain looks like it's coming from the wall areas, is the floor below the underlay the same, is it damp? Are the pipes for the CH in the wall at that point?

 

[Stef73]

The radiator valve and pipe are just in view to the left. The pipe goes in the ground which is concrete. To the right over in the corner is a box with some more pipework that comes down from the boiler which is up above in the back bedroom.
The floor is damp in the spot where I found the carpet wet yesterday.