Complex sentence: He retired from the BBC in 1972 on his sixtieth birthday, and became a freelance commentator and it was in that capacity that he continued to appear on TMS for the next twenty-two years.
Split into simpler sentences: He retired from the BBC in 1972 on his sixtieth birthday, and became a freelance commentator. It was in that capacity that he continued to appear on TMS for the next twenty-two years.