Simplify the following text for a Grade 10 native English-speaking person.
Original: An appointment as vicar-choral of St Paul 's Cathedral ( 1687 ) led another as lay vicar of the choir of Westminster Abbey ( 1699 ) .
Simplified: Besides his work at the king 's court he was also a vicar-choral of St Paul 's Cathedral and later a lay vicar of the choir of Westminster Abbey .