The BBC Singers are the professional chamber choir of the BBC. As one of six BBC Performing Groups, the 24-voiced choir has been in existence for more than 80 years. The BBC Singers has commissioned and premiered works by the leading composers of the past century, including Benjamin Britten, Sir Michael Tippett, Judith Weir and Sir John Tavener. It regularly performs alongside leading international orchestras and conductors, and makes invitational appearances at national events such as the funeral of Diana, Princess of Wales in Westminster Abbey.