There's no evidence of a previous rad - and the cable has nothing to do with the damp.
Others have mentioned previous remedial work - I can see a capped joist on the RH joist, & a wedged up joist on the left thats sitting on an off-cut of DPC or a slate?
What the purpose of the post is isn't too clear but all the timber in that area appears to be damp - the vent has been installed too high up the wall, and now seems to be venting into the room.
Previous pics showed rusty fixings, and damp failing floor boards.
I would suggest that a previous lack of through ventilation and a present water penetration through what looks like a solid wall might be the cause of your difficulties.
Others have mentioned previous remedial work - I can see a capped joist on the RH joist, & a wedged up joist on the left thats sitting on an off-cut of DPC or a slate?
What the purpose of the post is isn't too clear but all the timber in that area appears to be damp - the vent has been installed too high up the wall, and now seems to be venting into the room.
Previous pics showed rusty fixings, and damp failing floor boards.
I would suggest that a previous lack of through ventilation and a present water penetration through what looks like a solid wall might be the cause of your difficulties.