Really posh people have traditional names (I think some of the names in the list here are a bit 'frilly' for that - more upper middle/arty/boho/try-hard) but then acquire some really strange nicknames
Boys would be:Charles, James, John, William, George, Henry, Edward, Rupert, Alexander, Frederick, etc
Girls: Alexandra, Isabella, Charlotte, Anna, Catherine, Elizabeth, Victoria, Sophia, Georgina, Sarah, Harriet, Lucy