He and his first wife, Mariga (the former Princess Marie Gabrielle of Urach), founded the Irish Georgian Society in April 1958 to help to preserve Irish architecture of all periods. This was timely as the Irish planning laws were enacted only from 1963. Archiseek.com 404 Error

The IGS became involved in numerous projects and started publishing quarterly bulletins.Some early preservations or campaigns were at: Damer House (Tipperary), The Conolly Folly (Kildare), Mountjoy Square, Tailors' Hall and Hume Street (Dublin) and the Dromana Gateway (Waterford).

The IGS also held Georgian cricket matches played to the rules of 1744.

In 1967-79 the Guinnesses bought and started to preserve Castletown House, in Celbridge, Kildare, said to be the finest Palladian house in Ireland. Castletown House, Co Kildare (Alessandro Galilei & Edward Lovett Pearce) - Irish Architecture

In more recent years he has founded a scholarship for students of architecture. Contemporary and Historical Irish Architecture and Architects - Archeire - Irish Architecture Online

His conservation work has been recognised by many American and English cultural groups, and Europa Nostra.In 1980 he was made an honorary Doctor of Laws at Trinity College Dublin. In 2006 he was presented with a Europa Nostra award by the Queen of Spain. In 2010 he headed the Saint Patrick's Day parade in Seattle.

Married at Oxford in 1954 to Princess Henriette Marie-Gabrielle ("Mariga") von Urach, daughter of Prince Albrecht von Urach and a granddaughter of King Mindaugas II of Lithuania, by whom he had a son, Patrick Desmond Carl-Alexander, and a daughter, Marina:[1]. Desmond is also father of another son, Anthony (Anto), who is a very keen member of the Hash House Harriers. Through Patrick he is a grandfather of the fashion model Jasmine Guinness. Jasmine Guinness, Fashion model

In 1984 he married Penelope Cuthbertson, a granddaughter of the artist Nico Wilhelm Jungmann Obituary: Zita Jungman | News | The Guardian

He is the older half-brother (on his mother's side) of Max Mosley, former President of the FIA.

He has also been a member of Irish groups such as the Iveagh Trust, the CKAS, the RIAC Motorsport Ireland :: RIAC Archive and the Kildare Street & University Club.

• Portrait of Dublin (New York, Viking Press, 1967)
• Georgian Dublin (Batsford, B.T., Ltd.1979) ISBN 0-7134-1908-3

Three books with Julius Trousdale Sadler:

• Mr Jefferson, architect (New York, Viking, 1973) ISBN 0-670-49261-2
• Palladio: A Western Progress (New York, 1976) ISBN 0-670-53732-2
• Newport preserv'd : architecture of the 18th century (New York : Viking Press, 1982) ISBN 0-670-50938-8

With William Ryan:

• Irish Houses and Castles; with William Ryan. (London: Thames & Hudson 1973).
• The White House: An Architectural History (New York: McGraw-Hill, 1980). ISBN 0-07-054352-6

With Jacqueline O'Brien, wife of the famous racehorse trainer Vincent O’Brien:

• Dublin - A Grand Tour (Weidenfeld & Nicholson 1994)
• Great Irish Houses and Castles (Harry N. Abrams, Inc.) ISBN 0-8109-3365-9 (December 1998) and in paperback (Weidenfeld & Nicolson September 1993) ISBN 0-297-83236-0.

He has also written numerous articles such as:Thomas Jefferson: Visionary Architect. Horizon, 22 (1979): 51-55.

• Gannon, Charles: Cathal Gannon - The Life and Times of a Dublin Craftsman (Lilliput Press)
• Address on the award to Desmond Guinness of the European Union Prize for Dedicated Service to Heritage Conservation Irish govt. 2007.
• The peerage.com

Desmond Guinness