Permatanned is the adjective. In informal British talk, a permatanned person is a white person who always looks brown because they use sunbeds or skin-colour products, not because they live in the sun or because that is their natural colour. Same teasing tone as permatan: gossip, magazines, jokes about a tan that does not take a holiday in January. It is not a medical or scientific word, and it is not a kind default. You would not use it of someone who is naturally dark-skinned, or of someone who came back brown from one trip. The picture is a brown that looks put on and kept on.