The IGI has extracted records for the bapt of Thos Kelly son of Patrick Kelly & Esther Christian, on 13 Feb 1775 Ballaugh as Frances wrote, along with his two sisters Esther bapt 3 Sept 1769 Ballaugh, and Margt bapt 6 Sept 1772 Ballaugh (so the Esther will looks right).
Patrick & Esther married in Ballaugh on 8 Oct.1768.

There were other Thomas Kelly bapts around 1775 but not in Ballaugh or Maughold.
I had a look at the scan of the 1851 census page, and his birthplace was definitely given as Ballaugh, and also that he was married, not widowed.

Maughold bapts for the children of Thomas Kelly & Ann Hogg:
Esther [daur of] Thomas Kelly/ Ann Hogg [bapt] Parish Church 20 Jan 1799
Jane Thomas Kelly/ Ann Hogg Parish Church 4 Apr 1802
Robert Thomas Kelly/ Ann Hogg Parish Church 11 May 1806
James Thomas Kelly/ Ann Hogg Parish Church 16 Oct 1808
Thomas Thomas Kelly/ Ann Hogg Parish Church 3 Mar 1811
Margaret Thomas Kelly/ Ann Hogg Parish Church 20 Jun 1813
Catharine Thomas Kelly/ Ann Hogg Parish Church 15 Oct 1815
Alice Thomas Kelly/ Ann Hogg Parish Church 23 Apr 1820

Sue