Complex sentence: Talbot attended the City of London School before leaving at 17 to join the family business at the Fann Street type foundry; his regular writing began in 1879, when the "B.O.P." was launched.
Split into simpler sentences: Talbot attended the City of London School before leaving at 17 to join the family business at the Fann Street type foundry. His literary career began in 1879, when the "B.O.P." was launched.