The Ambler Family were prolific in and around Halifax in the 18th and 19th century. Despite this I cannot trace with any certainty the ancestors of John Ambler.
 

The memorial records for St. John's, Halifax record "In memory of John Ambler of Halifax who departed this life Dec 13th 1820 aged (4)1 years. Also Sarah, wife of the above John Ambler, who died Oct 19th 1855, aged 76 years". Helpfully it gives his wife's details as well and this pin-points that this is indeed John's grave. Although the age of 41 years is not certain (due presumably to the state of the gravestone when read), the age of 41 years is a sensible guess as it ties in with the age of his wife - they would both have been born about 1779.

Possible births of John are either the son of Issac Ambler (29th May 1779) or the son of John Ambler (9th April, 1778).