I am the voluntary OPC (on-line Parish Clerk) for the parishes of St Breock and Egloshayle (Wadebridge, in essence). One of the things I keep is a database of everyone I come across (currently about 20,000 individuals). From this, the only ANNEAR/POLKINGHORNE tie-in I can find is:
Richard POLKINGHORNE, born 1811 and was a Mason (1841 census relates). No other details of him are known.
On an u/k date he married Ann ANNEAR. She was born in 1810 at St Breockand Baptised in the local church on 17th June 1810 (although the 1841 census gives her dob as 1806).
She was the daughter of William ANNEAR (1764 to 1838) and Mary HENWOOD (1775 to 1850)and had siblings of Mary, Elizabeth, William, James and John
Richard and Ann had (according to what I have) only one child - a daughter Mary who died young (1839 to 1842) according to the local MI's.
Could these be the parents? If so, the date of birth of the "sister" would seem to fit, along with the fact that they all suddenly disappear from my Parish records.