William Blythe and Anne Marshall were married on 22.11.1849 in Clogher Cathedral. Tradition was to marry in the bride’s church so that should tell you the Marshall family were Church of Ireland and it was their parish church. Their records start in 1763, so you may be able to trace them back from that. There’s a copy in PRONI (the public record office) in Belfast.
https://civilrecords.irishgenealogy.ie/churchrecords/images/marriage_re…
William’s townland was Tamlaght. His father was a farmer and carpenter. Griffiths Valuation for Tamlaght (1860) lists William Blythe in Tamlaght. There was also a Thomas Blythe next door who is likely to be related. William had plot 2 which was a 27 acre farm. That farm today is up a lane off the Springhill Rd, between Ballygawley and Seskinore.
http://www.askaboutireland.ie/griffith-valuation/index.xml?action=nameSearch
No Blythes in Tamlaght by the 1901 census:
http://www.census.nationalarchives.ie/pages/1901/Tyrone/Cecil/Tamlaght/
Judging by the 1901 census the Blythes were also Church of Ireland so probably Clogher COI records should have that family too.
I don’t see a death in 1865 for Wm Blythe junior, nor one in the period 1864 to 1871. In 1871 there was one who died aged 81. That might be Wm senior. The certificate ois not available to view on-line free yet. You can view the original certificates on-line on the GRONI website, using the “search registrations” option:
https://geni.nidirect.gov.uk
You will need to open an account and buy some credits. It costs £2.50 (sterling) to a view a certificate.
Looking at the death records for the Clogher area, I note a couple of other Blythes there who were carpenters, so possibly it was a family trade.