My great grandad's younger sister was Fanny Gill Hardstaff. She married John James Moore, a miner and lived at 25 Victoria St., Selston, a short distance from Portland Row, Kirkby. When I researched the Moore family, like you, I discovered that John James had 3 sisters and 5 brothers, the youngest being Thomas Saville Foljambe Moore B 1880. As all the other siblings have family/ordinary names, it does make you wonder how he came to be so called. Also, his mother was the middle child of 5, again with a fancy name i.e. Celestina Anne Pamelina Lavinia Spencer B 1841 Blackwell, Derbyshire. Her family were framework knitters and there is nothing to suggest that wealth played any part in their lives.
Could it be delusions of grandeur? It's a real mystery!