I am wondering if this is the family in 1841:

At Baghay Farm where they were in 1851: PRO Ref HO 107/951/8

John Chard 55 (Should be James, but son John was called Jimmy)
Elizabeth 50
Amelia 20 (Should be Elizabeth but maybe called Amelia, because mother was Elizabeth)
William 20

I am wondering if the confusion was because their eight year old daughter had died in February.

I have looked for a Chard family in 1851 Census on Free Reg and I cannot find them.