Complex sentence: The Stones reef had always been a hazard to shipping and a lighthouse had been considered many times prior to 1858 but nothing came of plans until the SS Nile was wrecked in 1854 with the loss of all on board.
Split into simpler sentences: The Stones reef had always been a hazard to shipping and a lighthouse had been considered many times prior to 1858 but nothing ever came of any plans. The spur to action came when the SS Nile was wrecked in 1854 with the loss of all on board.