Complex sentence: The first civilian competitor to leave London was Anne Alcock the niece of Sir John Alcock, she was followed by a number of other runners including Stirling Moss, Mary Rand and Sheila Scott, who used her own private aircraft.
Split into simpler sentences: The first civilian competitor to leave London was Anne Alcock, the niece of Sir John Alcock. She was followed by a number of other runners including Stirling Moss, Mary Rand and Sheila Scott, who used her own private aircraft.