I did more stripping of the layers of paint / powdercoat from the frame. The forks were essentially devoid of chrome and had that yellow appearence of Nickel plate.
The head tube and down tube also have missing chrome but remnants of some plating, likely nickel again. There are areas of exposed bare 531 steel frame which rust over brown in double quick time suggesting that some chemicals are still about, there is also a dent on the downtube which looks like it's been filled in with molten lead or other metal. There is a very thin layer of gray primer under the white.....
Theory so far is..
1. Frame left the factory 1971 chromed like the one's we sold in the shop
2. someone stripped of the chrome chemically, filled in the dents with metal, applied an etch primer and the whole frame finished in white.
3. the white was painted over in blue in a thin layer
4. the whole frame was powder coated black.
There is no original chrome left so will think about white with chrome forks