Complex sentence: Dennis Williamson is a professional rugby league footballer who played in the 1950s, and 1960s, playing at club level for Whitehaven, and Wakefield Trinity (Heritage № 675), as a, i.e. number 11 or 12, during the era of contested scrums.
Split into simpler sentences: Dennis Williamson is a former professional rugby league footballer who played in the 1950s and 1960s. He played at club level for Whitehaven, and Wakefield Trinity (Heritage № 675), as a, i.e. number 11 or 12, during the era of contested scrums.