Just not Black and White?

There’s a goose at Holkham among the Brents. Some say it’s flanks aren’t chalky enough for Black Brant. It must be a hybrid. Some say the chinstrap doesn’t meet in the middle Others say the mantle isn’t black enough. I’ve even heard it said the black belly is not extensive enough. Looks good to me. Well within the range of variations I’ve seen in Canada.