This name tops every fashion maven's Santa Claus list. Treacy's magnificent hats regularly grace the pages of Harper's Bazaar; one-half Mad Hatter, one-half Cecil Beaton, Treacy's creations always guarantee Making an Entrance. Only the most serious fashion plates need apply, truly: the atelier is open by appointment only. Cheapskates can shoot along to Debenhams department store on Oxford Street, where Treacy has a diffusion line. Tube: Victoria.