idk if there's a set rule on what names the upper classes use or even what constitutes the upper classes. But I have taught in a private boarding school for more than a decade and have taught such a mixture of names, from all stereotyped categories and cultures. A selection for illustration:
Antigone, Sydney, Anastasia, Georgina, Harriet, Rebecca, Chantelle, Dakota, Jemima, Fenella, Atlanta, Hailie, Sarah, Charlotte, Deborah, Rhiannon, Iona, Amelia, Chloe, Nina, Carmen, Tallulah, Lili-Kitty, Millicent, Henrietta, Skye, Macarena, Chelsey, Arabella, Adesuwa, Christiana, Lola, Ellie, Clemency, Ava, Sorcha, Phoebe, Tongqiao, Fabia, Amreeta, Amber
Bailey, Ptolemy, George, Riley, Montgomery, Harrison, Rafi, Hugo, Hugh, Gennardy, Shea, Oluwatoni, Sebastian, Albert, Daniel, Cosmo, Frederick, Orlando, Gavin, Leopoldo, Toby, Felix, Charlie, Alfie, Ibrahim, Phineas, London, Teddy, Oliver, Maximillian, Laurence, Drew, Ashton, Jolyon, Arthur, Hardy, Guy, Lawson