Dear Brendan
Welcome to Ireland Reaching Out!
As you can see from the link below, Killanummery is a Civil Parish in Co. Leitrim:
http://www.irishtimes.com/ancestor/fuses/townlands/index.cfm?fuseaction…
Church of Ireland records for that parish begin in 1884 while records for the corresponding Roman Catholic Parish of Killanummery begin in 1828 for baptisms and 1827 for marriages. There are some missing dates though, between 1846 and 1848 for baptisms and 1846 and 1848 for marriages. While William?s birth is just on the cusps of those dates, it is a good idea to check the sites suggested below anyway, as often times people did not know their actual date of birth and sometimes the true date can be many years different from the assumed one.
There are some places where you can search online, however these websites do not have complete collections and many do not cover the period after 1900:
www.familysearch.org has a huge database of genealogical records including some church records for Ireland.
www.rootsireland.ie have a large collection of Irish Church records, however you have to pay to use this site.
Other important sources include the Tithe Applotment Books and Griffith?s Valuation. Even though these sources only record the head of the household, the information is very important and can be valuable:
Tithe Applotment Books (1823-1837): http://titheapplotmentbooks.nationalarchives.ie/search/tab/index.jsp
Griffith?s Valuation (1847-1864): http://www.askaboutireland.ie/griffith-valuation/
The National Archives of Ireland: http://www.census.nationalarchives.ie/search/ you can search the 1901/1911 Census on the National Archives page too, for instances of the family name at that time
Remember to post any new information that you find here. The more information you post, the more likely it is that one of our volunteers will be able to advise or assist you. Also include information concerning which sources you may have already used so others may further your search.
Best of luck with your search
Clare Doyle
Genealogy Support