Complex sentence: The playing style complemented the singing style of the choir in the cantatas and passions and their performances of the St Matthew Passion--and sometimes the St John Passion--were eagerly awaited annual events, generally given in prominent London churches.
Split into simpler sentences: The playing style complemented the singing style of the choir in the cantatas and passions. Their performances of the St Matthew Passion--and sometimes the St John Passion--became regular annual events, generally given in prominent London churches.