Graduating from Cambridge University, Posford planned a law career but the successful interpolation in an early 1930s touring version of Lavender of a song he had written with Rodney Hobson prompted him towards a new career. After studying at the Royal College of Music, Posford composed many songs, often with librettist-lyricist Eric Maschwitz. For radio, they wrote Goodnight Vienna, which then became a 1932 film, starring Anna Neagle and Jack Buchanan (US title: Magic Night), and a stage show. Posford and Maschwitz then wrote The Great Hussar (1933), which, revised and with additional music by Bernard Grun, opened at London’s Adelphi Theatre as Balalaika (1936) where it ran for 570 performances. The hit song, hastily written by Posford and Maschwitz, was "At The Balalaika". The 1939 film version starred Nelson Eddy and Ilona Massey. Maschwitz, Posford and Grun also composed Paprika (1938), which flopped, but a revised version, Magyar Melody, ran at His Majesty’s Theatre for 105 performances. To the original score was added "Mine Alone", composed by Manning Sherwin, which outlived the show.
Posford and Harry Parr-Davies composed Full Swing (1940), starring Cicely Courtneidge and Jack Hulbert, which had 468 performances during the London blitz. After the war, Posford co-composed Evangeline (1946) with Harry Jacobson. Starring Frances Day, this was a reworking by Maschwitz of James Laver’s Nymph Errant. In 1951, Posford was again in collaboration with Maschwitz, writing Zip Goes a Million. Starring George Formby, the show ran for 544 performances at the Palace Theatre and the songs included the title song, "Ridin’ Into Town", "The Thing About You", "It Takes No Time To Fall In Love", "Nothing Breaks But The Heart", "I Owe You", "Big Business", "Trouble With My Heart", "Thou Art For Me", "Ordinary People" and "I’m Saving Up For Sally". Posford and Maschwitz also collaborated on Happy Holiday (1954), a musical version of Arnold Ridley’s The Ghost Train. Among the songs from this show was "Sew A Silver Button On the Moon". Staged over Christmas, the show was another failure. Some of Posford’s melodies and themes appeared in the films The Good Companions and Britannia of Billingsgate (both 1933), and Invitation to the Waltz (1935). Posford also composed for the concert platform, these works including Transatlantic Rhapsody and Broadcasting House.
- Musical theatre
- Goodnight, Vienna (1931)
- Balalaika (1936); co-composed with Bernard Grün
- Evangeline (1946 musical) (1946); music also by Harry Jacobson
- Her Excellency (1949); co-composed with Manning Sherwin
- Zip Goes a Million (1951)
- Happy Holiday (1954)
- Film scores
- Goodnight, Vienna (1932)
- The Good Companions (1933)
- Balalaika (1939)
- Magyar Melody (1939)
- Full Swing (1942)
- Transatlantic Rhapsody (1942)