Walton was never a facile or quick composer, and in his final decade, he found composition increasingly difficult. He repeatedly tried to compose a third symphony for André Previn, but eventually abandoned it. Many of his final works are re-orchestrations or revisions of earlier music. He orchestrated his song cycle "Anon. in Love" (originally for tenor and guitar), and at the request of Neville Marriner adapted his A minor String Quartet as a Sonata for Strings. One original work from this period was his "Jubilate Deo", premiered as one of several events to celebrate his seventieth birthday. The British prime minister, Edward Heath, gave a birthday dinner for Walton at 10 Downing Street, attended by royalty and Walton's most eminent colleagues; Britten presented a Walton evening at Aldeburgh and Previn conducted an all-Walton concert at the Royal Festival Hall.