There definitly seems to be a link here with the names of the siblings and since Carnall is not that common a name. Also you state that Percy lived on Bobbin Mill Rd. I have Charles Henry(i) living at 1 Bobber's Mill Rd where my mother was born. I drove down the road when I was in England three years ago and saw the house. It is adjacent to a pub. Mom has said in the past that all the Carnall's lived in same area of Nottingham.
The two additional siblings (Bill & Nellie)are a total surprise. Do you have any spouses names, birth, marriage, death dates for any of them or the other siblings? I have some approximate dates I have pulled of the BMD indexes.
Some additional info I have:
Rose married either Percy or Joseph. May had two sons. May possibly married Len who was captured by Japanese in WWII but did come home after war. Charles Henry(i) was a miner, married Minnie Button.
Does any of this sound familiar?
I'll be speaking with my mother soon and will see if the occupations you mention for Joseph and Percy ring a bell. Unfortunately she left Nottingham early and was raised by grandparents so some of this time period is sketchy.
PS Dave Brown's father still lives in Nottingham I will pass this on to him off-line to makesure he sees it and perhaps he can confirm some with his dad.