Sebastian Ulick Browne, 12th Marquess of Sligo (born 27 May 1964), is a peer in the Peerage of Ireland. As Baron Monteagle he is also a peer in the Peerage of the United Kingdom. The Marquess holds the subsidiary titles of Baron Mount Eagle, Viscount Westport, Earl of Altamont, and Earl of Clanricarde, all in the Peerage of Ireland.
The son of Captain Lord Ulick Browne (1915–1979) and his second wife Fiona Glenn, he was educated at Rugby School. He married Christina Maria Suaznabar, of Bolivia, in 1984, by whom he has two children:
- Lady Camilla Browne (b. 1986)
- Christopher Ulick Browne, Earl of Altamont (b. 14 November 1988)
The couple divorced in 1992.
He emigrated to Australia in 1997, where he is a residential real estate agent. He succeeded his first cousin, the 11th Marquess, as 12th Marquess of Sligo in July 2014, although the 11th Marquess had dissolved the entail on the family estate of Westport House and left it to his daughters who sold it in 2017. On 22 January 2016, Lord Sligo married Claire Suzanne van Middelkoop in Wollongong.
- "No. 39851". The London Gazette. 12 May 1953. p. 2647.
- Montague-Smith, Patrick W., ed. (2008). "SLIGO, MARQUESS OF (Browne) (Marquess I 1800) Sits as BARON MONTEAGLE (UK 1806)". Debrett's Peerage and Baronetage 2008. London: Debrett's Peerage Limited.
- "Wedding Announcement". Sydney Morning Herald. 22 January 2016.
|Peerage of Ireland|
| Marquess of Sligo
Christopher Browne, Earl of Altamont
|Orders of precedence in the United Kingdom|
The Marquess of Headfort
|Order of Precedence of the United Kingdom||Followed by|
The Marquess of Ely