Yes they have. The Brits have always knighted musicians and composers.
Sir John Field, Sir Edward Elgar, Sir Thomas Beecham, Sir Clifford Curzon, Sir John Barbirolli, Sir Arnold Bax, Sir William Walton, Sir Arthur Sullivan, Sir Benjamin Britten, Sir Andrew Lloyd-Webber, Sir Georg Solti, Sir Colin Davis, etc.
Let me know when they get to “Sir Dusty Springfield,” or “Sir Lulu.” ;)