I found another tree for Thomas Dunkley and Mary Jefferies. According to that one, they had a son, John in 1814 but he died in the same year. They had a second son called John in 1823 which would make it too late for the one you are looking for.
There is another tree that shows John Dunkley, 1806, Towcester son of William Dunkley & Elizabeth. But he is shown as married to Ann Pierce.
The 1851 census suggests your John Dunkley was born in 1810. I found a birth of John, son of George & Mary, baptism 17 April 1808 in Paulerspury.
I'm not sure whether this helps or confuses more? Hopefully a few clues.
Debbie