Introduced by Jane Glover who also talks to tonight's soloist, the soprano Felicity Lott , and to Bernard Haitink , who conducts the BBC Symphony Orchestra leader RODNEY FRIEND Solo pianist John Alley This week's programme features two 20th-century masters of instrumental colour. Ravel: Sheherezade is a sumptuous evocation of the Orient. Originally planned as an opera, it crystallised into a ravishing song-cycle for soprano and orchestra. In Stravinsky: Petrushka the composer had in mind 'a distinct picture of a puppet, suddenly endowed with life.' His richly-scored ballet - set in the 1830s at a bustling Shrovetide fair in St Petersburg - reflects the dance theme of this year's Prom season, and is being performed in the original concert version Stravinsky made in 1911.