Lamp - Metal, Chrome

Chrome-plated lamp from the 1970s in excellent condition. Electrics are working just fine with an EU socket.
The colour is chrome over another metal beneath it. I can’t just tell you so much about the lamp, more than when I grew up, we had like 10 or eleven in our house (in Kenya). Some got lost in moving, and now I have three left, of which I'm selling one. This chromelamp is well taken care of and haven’t been used in over 40 years, just put I box with paper and nobody has touched it since.
I can’t tell you when the lamp was bought new, because the whole family who knew about it is gone now. But I’m 60, and they have been in my home as long as I can remember.
There are some stains as shown I one picture. It’s either some corrosion, a scratch or a stain. I don’t want to scratch too much in case I make it worse. But it’s located inside the bottom ring, so when it’s turned the right way, you never see it.

This is my own guess about our lamps: I think they are quite rare because I’ve been searching on internet for years and haven’t found out anything about them except that they are English and comes from CC Phosco Ware a company that are now manufacturing bigger works like lighting for airports, roads, motorways and more. And that is why I think this lamp is very rare because it doesn’t turns up anywhere when the company expanded.
I did find out that there was made a French copy of this exact lamp.