Styled Viscount Slane until 1974 and Earl of Mount Charles from 1974 until 2009, he succeeds his father in the marquessate and other titles in 2009. However, in the Republic of Ireland frequently, and erroneously, he remains referred to as Lord Mountcharles, his former courtesy title. He also inherits the U.K. peerage title Baron Minster, of Minster Abbey in the County of Kent, created in 1821 for his ancestor, the 1st marquess thereby giving the Marquesses Conyngham the automatic right to sit in the British House of Lords until 1999.
As Earl of Mount Charles, he unsuccessfully contests the Louth seat in 1992 for Fine Gael. In 1997 he stands for election to Seanad Éireann for Trinity College Dublin, and runs again without success as a Fine Gael candidate for the European Parliament in 2004.
Lord and Lady Conyngham divide their time between Beauparc House and Slane Castle in County Meath. The latter is the family’s principal ancestral seat until it is badly damaged by fire in 1992. The castle has now been restored.
The Marquess Conyngham enjoys a high profile in Ireland as the author of a weekly column in the Daily Mirror. He has been dubbed the rock and roll aristocrat or the rock and roll peer owing to the very successful series of rock concerts he has hosted since 1981, held in the natural amphitheatre on the grounds of Slane Castle. These concerts have included performances by The Rolling Stones, Thin Lizzy, Queen, U2, Bob Dylan, Bruce Springsteen, David Bowie, Guns N’ Roses, Oasis, and Madonna. Lord Conyngham receives the Industry Award at the 2010 Meteor Awards. In his autobiography Public Space–Private Life: A Decade at Slane Castle, he describes his business career and the challenges of being an Anglo-Irish peer in modern Ireland, and how being Anglo-Irish has gradually become more accepted there.