Part of the BBC Proms.Canadian organist Isabelle Demers makes her Proms debut, putting the Royal Albert Hall’s mighty 9,999-pipe organ through its paces. The rigour of Bach and Reger (born 150 years ago) contrasts with lighter pieces by Coleridge-Taylor and William Grant Still and a world premiere from Canadian composer Rachel Laurin. This is all framed with the drama of excerpts from stage-works by Wagner and Prokofiev.