Hi potteries phil.
I had a quick look on the Internet as I was interested to see what "Goldfinch" looks like. It's a beauty. I could easily find a space for it in my garden!.
As you say all the listings are in America, so if it was bred there we will probably have to wait until they start to propagate it here. No help to you I'm afraid, best of luck in your search. I will watch this posting with interest. If I should come across it I'll let you know.