Complex sentence: Brian Kellett is a professional rugby league footballer who played in the 1980s, playing at club level for Featherstone Rovers (Heritage № 623), and Mansfield Marksman.
Split into simpler sentences: Brian Kellett is a former professional rugby league footballer who played in the 1980s. He played at club level for Featherstone Rovers (Heritage № 623), and Mansfield Marksman.