I had a pair done last year by a small local plater. They charged me about £60 for the pair which included stripping off the old plating, polishing etc. They looked great but they polished off the rough grip section as I had ommitted to tell them what they were for! Still seem to work Ok.
Theres a place in Lowestoft, down near the fishing dock, have a look in yellow pages, did mine for £50 each, lewmar 46's. There is also a hard chromers down there, but I'm not sure if they do decorative stuff!
I had this problem a couple of years ago.
I had no success finding a suitable firm in East Anglia - they all do hard plating which they didn't recommend.
Try Vehicle and General Plating Co in Arlesley - thjey are versatile and v helpful.