Okay, so I paid the fee to access census data and tracked down Isabella. Virtually certain she's my great-grandmother.
1871 Census - Egton, nr Whitby
***********************************
Husband = John Pybus b. 1825 Lythe, Yorks – Farmer (employing 1 labourer)
Wife = Lucy M b. 1829 Aislaby, Yorks
Son = Frances b 1853 Sleights
Dau = Isabella b 1851 Sleights
************************************
This explains great-aunt Lucy Annie's name, and grandad being John Francis.
Isabella was one month old at the Census so was fibbing when she later claimed 1853. She and husband James were still in Stockton running the grocer shop in 1901.
Love to hear of any links.