eBay and Craigslist finds

http://www.carltoncycles.me.uk/mybikes/64constellation.htm

"all chromed with transparent copper acrylic painted over it. Carlton called this finish Acrilichrome.The effect can be seen where the paint still remains under the headstock badge. A very pretty, but probably not very durable, finish."

Cheers for that TomBurtonArt. I'd visited that site before but not come across that page or more likely hadn't read it properly...