Malcolm, the ethnic was tongue in cheek. Nowadays everything has become ethnic, food, music, literature, etc. Blood pudding, kippers and steak and kidney pie are considered ethnic English foods. Why not the OED, as JohninKansas suggests? It certainly has a different flavor from the American Webster's Collegiate, Webster's International, etc.

I think the whole "ethnic' nonsense was dreamed up (drempt up) to sell us on something exotic in order to make money on our attempts to be different from the people next door who stick with eggs and bacon or bangers and mash.