Complex sentence: The Wells Cathedral Voluntary Choir is a mixed adult choir of 30 members, formed in 1986 to sing at the midnight service on Christmas Eve, and invited to sing at several other special services.
Split into simpler sentences: The Wells Cathedral Voluntary Choir is a mixed adult choir of thirty members. It was formed in 1986 to sing at the midnight service on Christmas Eve, and was invited to sing at several other special services.