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The 1871 census shows a brother Robert for William:
1871RG10/3836 60 34
9 Albert RdWilliam Kermeen, head, 26, Joiner (Journeyman), b. Isle of Man
Elizabeth, wife, 27, b. Shropshire Westbury
William, son, 5 mo, b. Lancashire Waterloo
Robert, brother, unm, 24, Joiner, b. Isle of Man
John Evans, brother in law, 10, scholar, b. Shropshire Westbury
The William Kermeen/Elizabeth Evans marriage details are on
http://www.lan-opc.org.uk/Search/indexp.html , showing William's father as another William
Marriage: 15 Apr 1869 St Helen, Sefton, Lancashire, England
William Kermeen - Full Joiner Bachelor of Waterloo
Elizabeth Evans - Full Spinster of Waterloo
Groom's Father: William Kermeen, Miner
Bride's Father: William Evans, Book keeper
Witness: Edw. Kendrick; Caroline Rickard
Married by Banns by: Langdon Hawes curate
Register: Marriages 1864 - 1884, Page 89, Entry 178
From there, this 1851 census looks like a good match:
1851HO107/2523 92 13
Patrick, Isle of Man
FoxdaleWilliam Kermeen, head, 42, Lead MinerAnn, wife, 38
Eliza, dau, 14, Employed at home
John, son, 11, scholar
Mary, dau, 8, scholar
William, son, 6, scholarElizabeth, dau, 3
Robert, son, 4Sophia, dau, 2 mo
All born Patrick
http://pilot.familysearch.org/recordsearch has this christening:
William Kermeen, 8 Dec 1844, Patrick, Isle of Man
parents William Kermeen and Ann Kneale
There are a number of christenings to William Kermeen and Ann/e Kneal/e on the IOM , from 1835 on.
The 1841 census reference for the family is HO107/1465/10 3 2, possibly indexed as Hermens.