I think a lot of your shortlisted names are actually quite contemporary/trendy at present. I think there are two categories of 'posh' names - not sure which, if either, would be 'old money'.
- Very conventional, probably royalty inspired
Ideas:
Alice, Anne, Alexandra, Beatrice, Charlotte, Caroline, Diana, Elizabeth, Florence, Harriet, Henrietta, Isabel, Joanna, Jane, Katherine, Louisa, Matilda, Mary, Margaret, Rose, Rosemary, Sophia, Victoria
Albert, Arthur, Andrew, Alexander, Charles, Christopher, Edward, Frederick, George, Henry, Hal, James, John, Louis, Michael, Nicholas, Philip, Peter, Richard, Stephen, Sebastian, Victor, William
- fancy/frilly/horsey/a bit different
Ideas:
Angelica, Araminta, Arabella, Allegra, Antigone, Cassandra, Clarissa, Cordelia, Cressida, Evangeline, Felicity, Fenella, Francesca, Georgina, Gabriella, Genevieve, Hermione, Isadora, Juliette, Jocasta, Jacinta, Larissa, Lavinia, Miranda, Millicent, Madeleine, Natalia, Ophelia, Octavia, Persephone, Philippa, Penelope, Rosalie, Rosanna, Saskia, Tassita, Tabitha, Tallulah, Tamara, Thalia, Vanessa
Atticus, Barnaby, Cyrus, Crispin, Claude, Fabian, Hugh, Hugo, Leonardo, Maximilian, Montgomery, Rafferty, Ralph, Rollo, Rupert, Orson, Ptolemy, Phineas, Solomon, Theodore, Vincent, Xavier