Complex sentence: Warburton's potential as a runner was identified at 17 by John Duckworth, his employer at Hutch Bank cotton mill. Warburton competed as an amateur athlete between 1866 and 1879 before turning professional at 34.
Split into simpler sentences: Warburton's potential as a runner was identified at 17 by his employer at the Hutch Bank cotton mill, John Duckworth. He competed as an amateur athlete between 1866 and 1879 before turning professional at 34.