At least we are sorting out where some of the assumptions came from. Thanks to Carol who checked the Maughold parish register copy on film for us we now know that the "Jalloo" did not appear on William's bapt., as was given to you:
["Ellinor Callow christened 10 OCt 1813 Lonan Isle of Man
Ellinor married Thomas Corkil 21 july 1810 Lonan Isle of Man
They had the following Children
1 - William christened 12 May 1816 Jalloo
2- Thomas christened 10 Oct 1813 Lonan"]

So-far, there is no proof that Thomas & Elinor Corkhill's son William was the one who was at Jalloo in 1851, and had moved to Lancs by 1861.

There was a Maughold burial for a Thomas CORKILL ag.54 on Aug 29 1834.
[Will for CORKILL, Thomas 1834 Maughold Epis 2 0106434]: Thomas Corkill of the Ard, Kk Maughold, d.27th Aug (1834). Unto John Corkill his eldest son…. field commonly called and known by the name of Booiley Woar… to his son Thomas Corkill six sheep… to his son William Corkill four yearlings.. 2 Sept.1834. Witnesses Wm & Robert Joughin (of Jurby).

Thomas Corkill and Ellinor Callow married in 1810 in Lonan, and had 3 sons: John b.1811 Maughold, Thomas b.1813 Lonan, William b.1816 Maughold.
1841 Maughold census [ages rounded]:
3 20 83 Ard
John CORKILL 30 Ag lab Isle of Man
Eleanor CORKILL 60 Isle of Man
William CORKILL 20 Isle of Man

If this is the right family in 1841, this 1851 entry could also be theirs, with greatly reduced ages for the sons. In the 1851 Maughold census at Ballagorrey beg there is John Corkill Hd 32, Propr Farming 8 acres b. Maughold, with William Brother U 28 b. Maughold, and Eleanor, W[idow], 70, b.Maughold. There is a dark blot over her relationship to John, but apart from the reduced ages John could be the eldest son of Thomas Corkill & Ellinor Callow b.1811, and if so, William must be the younger son - still unmarried. Thomas the middle son b.Lonan emigrated to the USA.

If this turns out to have been Thomas's son William, it excludes him from being the William who was married to Jane at that time. This would have been missed before as being possibles to be this family because of the reduced ages given, but I can't see any other Maughold family it could have been.
Elinor CORKILL ag.78, Ard, Maughold, buried 13 Nov 1853.

However, this doesn’t mean that William son of Patrick Corkill & Cath Creech is correct – I can’t find him in 1841, and there were several William Corkill burials. And where was your William b.1816 and his son John b.c.1838, in 1841?

Sue