Too any to quote easily from my phone but thanks to you all for taking the time with sensible replies.
Balancing sounds the best initial course of action - will try that tomorrow.
To answer some specific questions:
Questions yes both rads feel cold at the bottom and def warmer at the top...
Resident plumbers of NSC does flushing a heating system actually work?
I’ve got a mixture of old and new plumbing/rads in a 4 bed semi detached house with two rads not working very efficiently and the rest fine. Bleeding the system doesn’t do anything - v limited air comes out and the water...