"Ages in the 1841 Census:
The census takers were instructed to give the exact ages of children but to round the ages of those older than 15 down to a lower multiple of 5. For example, a 59-year-old person would be listed as 55. Not all census enumerators followed these instructions."
Quoted from FamilySearch
Reflecting about this, maybe the Coal Miner was 54 years old (born about 1787) but had to state 50 on the census...
But, on the other hand, Willow said the Thomas Mountford born in 1791 and who was a collier, was still alive in 1851. So this would rule him out, in my opinion.
I have just learned that Knutton Heath is not Cross Heath:
On a "Map Centre of Early Georgian OS map showing the area of: Burslem, City Of Stoke On Trent" (viewed on archiuk.com), one can see that Knutton Heath is next to Knutton.
Also this:
"There was an iron stone mine in Knutton as early as 1314.
Between 1686 and 1929 there was a forge on Knutton Heath at which flat round iron plates were hammered out to make frying pans, subsequently manufactured in nearby Newcastle.
http://www.places.staffspasttrack.org.uk/.../child.asp...
http://www.search.staffspasttrack.org.uk/.../default.asp...
By the early 19th century a number of pits had been opened in the surrounding area to produce iron ore and coal for the blast furnaces.The population rose from 1,918 in 1851 to 4,464 in 1861 due to the establishment of these new ironworks."
[Quoted from https://www.facebook.com/KnuttonCommunityPage/posts/a-briefish-history-of-knutton-village-can-you-think-of-anything-that-should-be-i/804886189582415/]
Maybe this would explain that Thomas Mountford ("a farmer of Knutton Heath" in 1831 when his son Charles was born), became a collier... ???