I've had a look at the England family.As far as I can see George must have been a late-marrying son, bapt. 1761, of John England.George would have been about 50 when Lydia died and as a labourer he might well not have found another wife so there would have been a need to find someone to look after William otherwise he would have ended up in the Workhouse.It looks likely that that someone must have been on the Knutton side.
Lydia had a sister Mary (who had an illegitimate daughter by Joshua Woofenden) but she would have been William's aunt.
Another possibility is Mary daughter of William Knutton, also born 1808.As far as I can see William and Lydia would have been brother & sister so Mary would have been William England's cousin.Possibly it was William Knutton and his wife who looked after him.
What's the Census date & Mary's age?This would help pin down Mary.