Hi Mark,
As a general observation, ages in earlier census returns are more accurate than later ones, when people appear to get younger as they age. Also deaths/burials are often incorrect because details are given by others, unlike the marriage record.

Sylvia wrote:
(1861) Charles St, Peel, German (dist 1B) RG9/4428 f.15 p.21 sch.129 [Collester]
William Callister h m 50 farmer of 36 acres German
Emily w m 47 German
John s un 17 Tailor German
Caesar s un 12 Scholar German
&
(1851) Close e Garey, German HO 107/2523 f.202 p.20/21 sch.74 [as DJD]
William Callister h m 41 Landed prop. Farming 35 acres German
Amelia w m 39 German
Maria d u 19 Household German
William s u 18 Farmer’s son German
Louisa d u 16 Household German
Elizabeth d 12 Scholar German
Ellinor d 10 Scholar German
John s 7 German
Casar s 2 German

Regarding John's occupation, have a look at the 1861 census and the way "Son" and "Scholar" were written right down to the bottom of the page. The only difference between the "S" and the "T" in tailor was a tighter half-loop at the top - otherwise they are identical. Also look at Shimmin on the next page, most of which look as though they start with T. Yet "Servant" next to Eliza Ann Shimmin aged 14 is written like a normal "S"! - Compare this Servant "S" with Scholar written directly below it which again looks like Tcholar. The loop on the "T" of Thomas A Gorry aged 7 (above the Callister family) is quite different, with a wide horizontal stroke across to the "m" - you can see it on the same screen as John's occupation, 4 lines below.
I'm now wondering whether it was meant to be Sailor in both 1861 and 1871.

Sue