The only Thomas McCloy I can see in the 1831 census was resident in Clagan. Perhaps that?s your family?
Looking at Griffiths Valuation for 1859, there?s a Thomas McCloy in Clagan (can?t say whether it?s the same one as in 1831). He?s on plot 5 which was a farmhouse, outbuildings and a half acre. Next door was Wm McCloy on plot 4 and John on plot 3, both with small farms. They?d likely be relatives. These 3 properties today are on Clagan Park, just off the Agivey Rd, north of Kilrea.
You can follow the ownership of these properties, forward, right up to 1929, using the revaluation records, which are on-line and can be found on this link:
http://www.proni.gov.uk/index/search_the_archives/val12b.htm
There was still one McCloy farm there in 1901:
http://www.census.nationalarchives.ie/pages/1901/Londonderry/Agivey/Clagan/1516081/
In 1911:
http://www.census.nationalarchives.ie/pages/1911/Londonderry/Agivey/Clagan/651989/
The above couple appear to be James McCloy and Sarah Reid. Their marriage was registered in Coleraine on 7.8.1863.
http://www.census.nationalarchives.ie/pages/1911/Londonderry/Agivey/Clagan/651990/
This couple may be John McCloy and Mary Nelson, whose marriage was registered in Coleraine on 26.6.1864.
You can look at both certificate son-line on the GRONI site for ?2 each should confirm whether they both hailed from Clagan, and also what their fathers? names were.
These families were Presbyterian so for early records you would need to search the Presbyterian churches in that area, notably Aghadowey, Kilrea 1st & 2nd and perhaps Killaig. (Copies are held in PRONI, Belfast). Kilrea 2nds are on the rootsireland site (subscription) but the others are not on-line anywhere so far as I am aware.
This site has a record of Ann McCloy of Clagan marrying on 1.12.1845. her father was Wm McCloy. She married James Duncan.
http://www.torrens.org.uk/Genealogy/BannValley/church/AghadoweyP/Marria…