Complex sentence: Prior to broadcasting, TVS refused to take on most of Southern's series except the arrangement to cover two Glyndebourne operas each year; with the advent of Channel 4 a year later, the operas were shown on Channel 4.
Split into simpler sentences: Prior to broadcasting TVS refused to take on most of Southern's series except the arrangement to cover two Glyndebourne operas each year. With the advent of Channel 4 a year later the operas were shown on Channel 4.