Complex sentence: Chester has a cathedral choir of male lay clerks, boy trebles and since 1997 the cathedral has recruited a choir of girl choristers, who sing on alternate Sundays to the boys and the same number of weekday services.
Split into simpler sentences: Chester has a cathedral choir of male lay clerks, boy trebles and since 1997 the cathedral has recruited a choir of girl choristers. The boys and girls sing on alternate Sundays and the same number of weekday services.