I quickly found lots of information on her family, including this interesting name, Jane Curgenven, who was Elizabeth Nicholls mother.Well that certainly looked like a Cornish name, and an easy one to trace, owing to it's unusual-ness. I googled the name to see what I could discover, and found an interesting webpage done by a dedicated researcher of the surname.
His conclusion -- it was a made up name! The original name was Lean! Jane's father was John Curgenven, and his father was John Lean.
Here's his info:
The very Cornish sounding name CURGENVEN appears to have been an invention by the Reverend Thomas LEAN (born 1644 in Lelant, Cornwall - died 1712 at Folke, Dorset), Educated at Exeter College, Oxford, in 1680 Married Dorothy PITT (of the family that produced the two William PITTS ). Headmaster of Sherborne school Dorset (1683 - 1695) and then Rector of the nearby Parish of Folke.
It can only be speculation as to why he changed his name, perhaps he thought LEAN too common a name for his position, but why CURGENVEN? there is no prior record of this name. His brother William had married a Rachel RICHARD whose family had earlier used the alias VENVYN but why would that be a reason to change your own name?
Rev Thomas and Dorothy had no issue, so how did the name created by him propagate? His brother William died in 1689 and William's widow Rachel died in 1692 leaving their children orphaned, William and Rachel's sons John, Thomas and Peter were looked after (no record of adoption found ) by the Rev Thomas ( their names changing to CURGENVEN ) and were found positions with the East India Company ( Rev Thomas's brother-in-law was Thomas 'Diamond' PITT, Governor of Madras. ) William and Rachel's fourth son Richard also took up the alias CURGENVEN as did the family of the Rev Thomas's other brother John.