On a visit to Truro Cathedral, I heard the organist practising, playing what I recognised to be the final piano section from 'Prologue' by Renaissance. I captured the performance on video, and discovered that the piece, obviously by J S Bach, was the C Major prelude, BWV 553, published in 'Eight Short Preludes and Fugues'.
I had recently obtained Cubasis AV, and used it to transcribe the first section of the Bach prelude. The audio was recorded from the computer sound card to CDR then ripped to mp3.