Complex sentence: From a young age he showed considerable interest in horse racing and left Mordialloc-Chelsea High School aged 14 to take up a post as an apprentice to trainer F. H. Lewis who was his great uncle and brother to Robert Lewis also a jockey.
Split into simpler sentences: From a young age he showed considerable interest in horse racing and left Mordialloc-Chelsea High School aged 14 to take up a post as an apprentice jockey. He worked initially under trainer F. H. Lewis who was his great uncle who was the brother of Robert Lewis also a jockey.