Complex sentence: John Clark (birth unknown--January 2011 (aged 71)) was a British professional rugby league footballer who played in the 1950s, and 1960s, playing at club level for Castleford, Wigan and Warrington.
Split into simpler sentences: John Clark (birth unknown--January 2011 (aged 71)) was a British professional rugby league footballer who played in the 1950s, and 1960s. He played at club level for Castleford, Wigan and Warrington.