His early work found its stimuli in extra-musical ideas. Several early works have their origins in medieval symbolism and iconography, notably three pieces for chamber ensemble: "Theatrum" (1996), "Torturous Instruments" (1997-8, after Hieronymous Bosch's depiction of Hell from The Garden of Earthly Delights), and "The Circling Canopy of Night" (1999). The latter of which was Hesketh's first piece to gain international attention. Commissioned by the Birmingham Contemporary Music Group and Faber Music, it was first conducted by Sir Simon Rattle and further championed by Oliver Knussen, who performed many of Hesketh's works. Performances at the Promenade Concerts at the Royal Albert Hall, London (London Sinfonietta) and the Concertgebouw, Amsterdam (ASKO Ensemble) soon followed. Described as "a glistening whirl of nocturnal colours, a driving sense of purpose and onward movement", the piece was received positively.