I have been researching the Moon tree for some time. I do believe that William b 1851 was the son of Philip Moon. Philip and Mary Ann Elphick were married in 1852. Maybe they would have been married sooner had Philip Moon not been away at sea so often!? On the 1871 census for New Shoreham, you will find Mary Ann at home with her children and Philip is enumerated as Philip Elphick Moon.