| Viscountcy of Gormanston | |
| Creation Date: | 7 August 1478 |
| First Holder: | Robert Preston, 4th Baron Gormanston |
| Present Holder: | Jenico Nicholas Dudley Preston, 17th Viscount Gormanston |
| Heir Apparent: | The Hon. Jenico Francis Tara Preston |
| Subsidiary Titles: | Baron Gormanston Baron Gormanston, of Whitewood |
| Status: | Extant |
| Former Seat: | Gormanston Castle |
Viscount Gormanston is a title in the Peerage of Ireland created in 1478 and held by the head of the Preston family, which hailed from Lancashire. It is the oldest vicomital title in the British Isles; the holder is Premier Viscount of Ireland.
The Preston family descends from Sir Robert Preston, who served as Lord Chancellor of Ireland. Sometime between 1365 and 1370 he was created Baron Gormanston by writ to the Parliament of Ireland. His son and heir, the second Baron, played a prominent part in public affairs, and was arrested for treason in 1418. His great-grandson, the fourth Baron, served as Lord Deputy of Ireland: in 1478 he was created Viscount Gormanston in the Peerage of Ireland. His son, the second Viscount, served as Lord Justice of Ireland in 1525. A later descendant, the seventh Viscount, was a supporter of King James II and was outlawed after the Glorious Revolution.
Jenico Preston helped to suppress the Irish Rebellion of 1798,[1] and in 1800 he had the outlawry reversed and was summoned to the Irish House of Lords as the twelfth Viscount Gormanston. He was the great-grandson of Anthony Preston, the de jure ninth Viscount Gormanston, the nephew of the seventh Viscount. The twelfth Viscount was succeeded by his son, the thirteenth Viscount. In 1868 he was created Baron Gormanston, in County Meath, in the Peerage of the United Kingdom, which gave the Viscounts an automatic seat in the House of Lords. His son, the fourteenth Viscount, notably served as Governor of British Guiana and as Governor of Tasmania. The 15th Viscount was a Captain in the Royal Irish Fusiliers and a Deputy Lieutenant for County Meath. the titles are held by the latter's great-grandson, the seventeenth Viscount who succeeded to the titles in 1940 at the age of seven months after his father was killed in action during the Battle of France during the Second World War.
Another member of the Preston family was Thomas Preston, 1st Viscount Tara. He was the second son of the fourth Viscount Gormanston. Also, John Preston, 1st Baron Tara, was a descendant of a younger brother.
The unusual first name Jenico borne by many Preston boys derives from the Gascon-born soldier Sir Jenico d'Artois, a prominent military commander who became a substantial landowner in Ireland. His daughter Jane married the 3rd Baron Gormanston, and was the mother of Sir Robert Preston, who was created a viscount.
The family seat was Gormanston Castle, County Meath, close to the county border with Dublin.