Oh, I'm wrong am I?. Have a look at this BBC link. It confirms we're all right. It has been claimed by everyone and their cat. Of course the Scots shouted the loudest, but nothing unusual there!
I note that nowhere else is mentioned. Coincidence? No, I think not.
PROVENANCE: hazy; somewhere in the UK. Various stories abound. Said to have originated between 1950s and 1970s and birthplace is sometimes cited as a Glasgow curry house. Legend has it one obstinate diner demanded gravy on tandoori chicken. A bemused chef responded by adding tin of Campbell's tomato soup and pinch of spices, unwittingly partaking in early example of fusion cookery.
"The first duty of Port is to be red" Ernest H. Cockburn