Simplify the following text for a Grade 6 native English-speaking person.
Original: Between 1958 and 1987 the LBS choir under Steinitz performed all the extant church and secular cantatas , 208 separate works , cantatas by Johann Sebastian Bach in various venues , and mostly for several years in the Church of St Bartholomew-the-Great , London .
Simplified: Between 1958 and 1987 the LBS choir performed all the cantatas by Bach which survive . 208 of them are known .