I want to thank everyone who has tried to help with this query. It's not resolved, and I am still missing Easter/Esther/Hester Blount's birth between 1776 and 1779. But your inputs have been helpful.
When Easter married Robert Grant in November 1800, both said they were from Great Glen, Leicestershire, although he was almost certainly from a Kibworth Beauchamp family. So, I guess Easter could also be from somewhere else (but almost no Blounts in Kibworth). Perhaps he moved away looking for work, before returning to Great Glen where there were more distant family members. As fellow researchers have kindly suggested, people moved around perhaps more than we think. And perhaps there are missing sections in the Great Glen parish register in the 1770s. It could be the brick wall, sadly.
