Task: Question Generation
Input (English): Passage: With the South London  Orchestra temporarily disbanded because of the war, Tippett returned to teaching at Hazelwood. In October 1940 he accepted the post of Director of Music at Morley College, just after its buildings were almost completely destroyed by a bomb. Tippett's challenge was to rebuild the musical life of the college, using temporary premises and whatever resources he could muster. He revived the Morley College Choir and orchestra, and arranged innovative concert programmes that typically mixed early music (Orlando Gibbons, Monteverdi, Dowland), with contemporary works by Stravinsky, Hindemith and Bartók.
He continued the college's established association with the music of Purcell; a performance in November 1941 of Purcell's Ode to St Cecilia, with improvised instruments and rearrangements of voice parts, attracted considerable attention. The music staff at Morley was augmented by the recruitment of refugee musicians from Europe, including Walter Bergmann, Mátyás Seiber, and Walter Goehr who took charge of the college orchestra.A Child of Our Time was finished in 1941 and put aside with no immediate prospects of  performance. Tippett's Fantasia on a Theme of Handel for piano and orchestra was performed at the Wigmore Hall in March 1942, with Sellick again the soloist, and the same venue saw the première of the composer's String Quartet No. 2 a year later. The first recording of Tippett's  music, the Piano Sonata No. 1  played by Sellick, was issued in August 1941. The recording was well received by the critics, Wilfrid Mellers predicting a leading role for the composer in the future of English music. In 1942, Schott Music began to publish Tippett's works, establishing an association that continued until the end of the composer's life.The question of Tippett's liability for war service remained unresolved until mid-1943. In November 1940 he had formalised his pacifism by joining the Peace Pledge Union and applying for registration as a conscientious objector. His case was heard by a tribunal in February 1942, when he was assigned to non-combatant duties. Tippett rejected such work as an unacceptable compromise with his principles and in June 1943, after several further hearings and statements on his behalf from distinguished musical figures,  he was sentenced to three months' imprisonment in HM Prison Wormwood Scrubs. He served two months, and although thereafter he was technically liable to further charges for failing to comply with the terms set by his tribunal, the authorities left him alone.
Output (English): When did Tippett formalize his joining of the Peace Pledge Union?