Complex sentence: After 20 years in show business, he got his television break on "Who Do You Do?", an ITV showcase for up and coming entertainers and impressionists, where they impersonated a host of stars, including Robert Mitchum and Mick Jagger.
Split into simpler sentences: After 20 years in showbusiness, Gee got his television break on "Who Do You Do?", an ITV showcase. The show gave the opportunity for up and coming entertainers and impressionists to impersonate a host of stars, including Robert Mitchum and Mick Jagger.