[2] Jacob was educated at Dulwich College, and enlisted in the Queen's Royal Regiment (West Surrey) at the outbreak of the First World War.
There, he was a pupil of Charles Villiers Stanford and Ralph Vaughan Williams (composition), Herbert Howells (music theory) and Adrian Boult (conducting), from whom he learned the "economy and decision" of his podium technique.
[1][6] At the end of his student course in 1924, Gordon became a teacher of music, briefly at Birkbeck and Morley Colleges, and then at the RCM, where he remained until his retirement in 1966.
[3] Among his students at the RCM were Malcolm Arnold, Ruth Gipps, Imogen Holst, Cyril Smith, Philip Cannon, Pamela Harrison, Joseph Horovitz, Bernard Stevens and John Warrack.
It was always denied that Glock had a blacklist,[8] but music by non avant-garde composers, including Edmund Rubbra, Arnold Bax, John Ireland and even William Walton, was demonstrably out of favour with the BBC during the 1960s.
[9] By this decade a large proportion of a composer's income came from royalties for broadcasts, and like others of his generation, Jacob suffered from the BBC's disinclination to play his music.
[11] His biographer (and former pupil) Eric Wetherell writes that as a composer, Jacob was influenced more by early 20th-century French and Russian examples rather than the German tradition.
[10] Among the original compositions from Jacob's later years was incidental music to a dramatised adaptation of the biblical Book of Job, first performed at the Festival of the Arts, Saffron Walden, and later broadcast by the BBC.
[18] Jacob's first major success was written during his student years: the William Byrd Suite for orchestra based on the Fitzwilliam Virginal Book.
[20] Most of Jacob's ballet scores were arrangements of existing works, such as Les Sylphides (1932, using music by Chopin), Carnival (1932, Schumann), Apparitions (1936, Liszt), and Mam'zelle Angot, (1947, Lecocq).
In 1968, Jacob re-orchestrated the score of Frederick Ashton's ballet Marguerite and Armand, replacing a previous orchestration by Humphrey Searle of music by Liszt.
Shortly after the war, on Boult's recommendation, Jacob was commissioned by a music publishing firm to orchestrate Elgar's Organ Sonata (1946).
After a single performance in 1947 this version remained unplayed until 1988, when the Royal Liverpool Philharmonic Orchestra conducted by Vernon Handley recorded it for CD.