Hi Gents thanks for the feedback, I decided to keep this original so it is running,
a 5 speed Huret Svelte derailleur.
The hanger bolt on the rear wheel would have finished her off, my spare parts bin was ransacked - no joy, but she was snapped up by a fellow Carlton lover and is now thrashing the hills and valleys of North Wales.
She was a joy to restore and my second full re-paint, there is an excellent automative paint shop close by and the boys did a great job on matching the paint before I stripped the original paint off (which was completely shot). My shed makes a perfect paint booth and I used rattle cans, taking care to apply light coats.
Latest main project is a Carlton Pro-Am, stripped down to the bone, I really like the original pearlescent paintwork on this, it does have some "Patina" rust spots, so I may sand and prime them, then get a can or 2 matched up for touch ups, before a couple of clear coats.