Thanks for the info. I have accessed various Census returns, and discovered that in 1861 Robert Quilliam at that time a Commercial Traveller and wife and small son William H were living next door to Samuel Quilliam and his family. He was aged 51 and a Watch Manufacturer and employer, born in Liverpool, so a very likely candidate as Robert's father. I found Robert's marriage refs and have sent for his wed cert, so that should confirm or destroy this theory. I read on another website that Captain John had no children, but three brothers, so Samuel could have been one of their children, but not a direct descendant as claimed. William Henry was educated on the Isle of Man (he is included in the 1871 Census there) so there must have been some kind of Manx connection.