Complete the following sentence: The "Prelude on the hymn tune 'Rhosymedre'" by Ralph Vaughan Williams was played at the
️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk> It was also played at the weddings of her two sons: Prince William (in April 2011) and Prince Harry (in May 2018).