The Royal Cornwall Gazette of 10th June 1836 has an advert for a 99 years lease of land in Penryn, Cornwall “late in the occupation of Richard Warmington.” So this might be land belonging to Richard which was put up for sale following his death. (Or it might be a different Richard Warmington altogether).
I searched the British Newspaper Archives for reports of Richard’s marriage c 1818 and for his death in 1836 but without success. If he had been gentry or nobility you might expect both events to be reported.
If the Warmington family were genuinely nobility (ie Lords) then they should be listed in Debretts or Burkes Peerage, both of which are available on-line (pay to view). You might want to look into those.
A grant of land in Ireland by the king in 1799 (George III) seems a bit late for me. Most of the major Irish land grants in Armagh and Ulster generally were made at the time of the Plantation (1610 – 1625) or after the 1641 uprising when some was declared forfeit. By 1799 nearly all land in Ireland belonged to someone else (and not the King). The family may well have acquired land in Armagh in 1799 but it probably wasn’t directly from the King.
I looked in the Irish Registry of Deeds records for the late 1790s (available on Family Search) and I don’t see any deeds to Warmingtons at all, nor are there any in PRONI's indexes, in Belfast. Perhaps the timing is out a bit. You might want to search the indexes further looking at later years.
The tithe applotment records c 1831 list these 6 Warmingtons farming in Armagh. There were no other Warmington farmers elsewhere in Ulster at that time.
Warmington, James-- Townland: Ballier Year: 1832-Lisnadill-Armagh
Warmington, James-- Townland: Ballybrawley Year: 1832-Lisnadill-Armagh
Warmington, John-- Townland: Tullyvallon Hamilton Year: 1830-Newtownhamilton-Armagh
Warmington, Joseph-- Townland: Ballier Year: 1832-Lisnadill-Armagh
Warmington, Joseph-- Townland: Tullyvallon Hamilton Year: 1830-Newtownhamilton-Armagh
Warmington, Widow - Townland: Tullyvallon Hamilton Year: 1830-Newtownhamilton-Armagh
The 1766 Religious census for Creggan, Co Armagh lists a Josh(ua) Warmington then, suggesting that branch of the family was resident in the area in the mid 1700s.
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