In 1957, he moved to the Royal Ballet at the Royal Opera House, Covent Garden,[7] where he shared the rostrum with Malcolm Sargent, Ernest Ansermet, Arthur Bliss, William Walton, Hans Werner Henze and Benjamin Britten, from whom he took over Britten's original production of The Prince of the Pagodas.

[7] As principal conductor of the Yomiuri Nippon Symphony Orchestra in the 1960s, Alwyn conducted the first performance in Japan of Gustav Holst's The Planets, and introduced other British works to Japanese audiences.

The series culminated in a performance of Benjamin Britten's Let's Make an Opera and was part of a pioneering educational movement, led by John Hosier, to teach music in schools through the medium of television.

Alwyn also presented a BBC Omnibus documentary on the music of Tchaikovsky, directed by Sir John Drummond.

[11] To mark the year of his 80th birthday, Alwyn was interviewed by Edward Seckerson for BBC Radio 3's programme Stage and Screen, broadcast on 21 November 2005.

The programme notes record that "Alwyn's career has encompassed many of the highlights of post-war British musical theatre".

Other notable recordings include Lord Berners' Wedding Bouquet with the RTÉ Chamber Choir and Sinfonietta (1996 Gramophone Critics' Choice).

[29] A collection of main themes and excerpts from famous film scores, including The Last of the Mohicans, The English Patient and Sense and Sensibility was also selected as a recording of the year by the magazine in 1998.

[6] Alwyn devised and conducted a gala concert in aid of Imperial Cancer Research Fund (now a constituent charity of Cancer Research UK) for the 1993 St George's Day Festival, for which he wrote much of the original music, featuring the BBC Concert Orchestra, the Royal Artillery Band, St George's Singers, St George's Festival Choir and the Wells Cathedral Junior School Choir.

Starring Peter Vaughan as St George, it was broadcast from the Royal Albert Hall on BBC Radio 2.

The title of the work refers to a famous photograph of a young Princess Elizabeth wearing a Grenadier Cap at the time when she became Colonel of the Regiment in 1942.

Alwyn composed the theme tune for the LWT series Affairs of the Heart (1974-1975),[43] a set of adaptations of the stories of Henry James, and he was also commissioned to write the music for the television adaptation of Sir John Mortimer's play A Choice of Kings, which commemorated the 900th anniversary of the Battle of Hastings.

Alwyn said[44] that his interest in Coleridge-Taylor's work began when his first dance band, 66 Squadron (Croydon) Air Training Corps, played Demande et Réponse in 1942.