The organ of the Martinikerk, Gronigen. Instantly recognisable by its opening mordent, the Toccata and Fugue in D minor BWV565 is firmly embedded in the public imagination as one of the highlights of the organ repertoire - and cue 'The Bach Toccata and Fugue' on the soundtrack whenever Hollywood cuts to an ecclesiastical interior (preferably with evil goings-on in the background). No Bach original manuscript survives, and organists and music scholars have long contested the piece's authorship. Now Fugue State Films have released Bach: The Great Toccata, a DVD-CD boxset exploring the story of BWV565, presented…