Although he had initially declined the commission, Delius was persuaded to write the incidental music for Hassan by the actor and director Basil Dean in July 1920, for performances he was planning for His Majesty's Theatre, London, the following year. Much of the music was drafted within a few weeks, and the score would eventually prove one of the greatest successes of Delius's career. Dean's plans for the project encountered significant obstacles and delays, however, and he had to commission additional music from Delius to cover the production's complex scene changes. The London première eventually took place on 20 September 1923 and was a critical sensation. Flecker's play is a sinuous double-narrative that intertwines the twin stories of the lovelorn but worldly-wise Hassan, confectioner at the court of the cruel and vindictive Caliph Haroun al Rashid (called Haroun ar Rashid in Flecker's play), and the young lovers Pervaneh and Rafi, caught up in the aftermath of a failed uprising and condemned to a terrifying and brutally protracted death. In tone and setting, Flecker's text drew on nineteenth-century English translations of One Thousand and One Nights as well as other heavily fictionalized accounts and travel literature. Very much a product of the racial and class-based attitudes of it's time, the play revels in imaginary scenes of a despotic Eastern court and it's gruesomely barbaric practices.