Complex sentence: Dennis Horner was a professional rugby league footballer who played in the 1940s, and 1950s, playing at club level for Wakefield Trinity, as a, i.e. number 9, during the era of contested scrums.
Split into simpler sentences: Dennis Horner was a professional rugby league footballer who played in the 1940s, and 1950s. He played at club level for Wakefield Trinity, as a, i.e. number 9, during the era of contested scrums.