[[File:Barnewall, Barons Trimlestown crest.jpg|300px|thumb|Barnewall, Barons Trimlestown crest.
The barony became dormant on the death of the sixteenth Baron, in 1879. In 1891 the peerage was claimed by Christopher Patrick Mary Barnewall (de jure 17th Baron Trimlestown), a descendant of Hon. Patrick Barnewall, second son of the seventh Baron. He died before he had fully established his claim, but in 1893 his younger brother Charles Aloysius Barnewall was confirmed in the title by the Committee for Privileges of the House of Lords.
the title was held by the grandson of the successful claimant of 1893, the twenty-first Baron, who succeeded his elder brother in 1997. There being no known heir to the barony, on the death of the 21st Baron on 10 January 2024, the title became dormant, and may be extinct, unless a remote heir is found.
- John Thomas Barnewall, 15th Baron Trimlestown (1773–1839)
- Thomas Barnewall, 16th Baron Trimlestown (1796–1879) (dormant 1879)
- Christopher Patrick Mary Barnewall, de jure 17th Baron Trimlestown (1846–1891)
- Charles Aloysius Barnewall, 18th Baron Trimlestown (1861–1937) (confirmed in title 1893)
- Charles Aloysius Barnewall, 19th Baron Trimlestown (1899–1990)
- Anthony Edward Barnewall, 20th Baron Trimlestown (1928–1997)
- Raymond Charles Barnewall, 21st Baron Trimlestown (1930–2024)
There is no known heir to the barony.
thumb|right|The grave of Charles Aloysius Barnewall, 19th Baron Trimlestown at [[St Mary Magdalen Roman Catholic Church, Mortlake in December 2021]]
See also
- Viscount Barnewall