The Trevors are direct descendants of a union which took place in 942 between Tudur Trevor, King of Gloucester, and Angharad, daughter of Howel Dda, King of Wales.
However, the family can trace their heritage back to the marriage of Severa, daughter of the Roman Emperor, Maximus, who died in 388 and Gwrtheyrn Gwrtheneu (Vortigen), the 82nd King of Britain.
They are also descendants of Llewellyn the Great, Prince of Wales (1194-1240), and the Kings of Ireland, and the present Prince of Wales inherits his most recent Welsh and Irish blood through the Trevor Family.
The founder of the family fortune during the Middle Ages was Sir Edward Trevor, though the name Trevor became fixed in the time of John Trevor (d 1453).
Sir Edward went to Ireland with Edward Blayney of Gregynog, Montgomeryshire, as a captain in the expedition sent to Ireland after the battle of the Yellow Ford in 1598.
Captain Trevor built on land at Stranmillis and Malone, near Belfast, where he settled some English families.
He married secondly Rose, daughter of the Most Rev James Ussher, Lord Archbishop of Armagh, and acquired an estate in County Down, which he called Rostrevor (a variation of Rose Trevor).
In 1619, he built the present mansion of Brynkinalt in Denbighshire, later enlarged by the 2nd Viscount Dungannon.
Sir Edward died in Ireland in 1642 and was succeeded by his eldest son, John Trevor, who died about 1643.
Sir Marcus Trevor (1618-70), one of Sir Edward's sons by his second marriage, was later created VISCOUNT DUNGANNON and Baron Trevor, of Rostrevor, County Down, in 1662, by CHARLES II, as a reward of his good services in the Battle of Marston Moor in the county of York, in which battle he encountered Oliver Cromwell and wounded him with his sword.
Lord Dungannon died in 1670 with no heirs, and the title became extinct.
JOHN TREVOR'S SON, Sir John (1638-1717), became Speaker of the House of Commons and Master of the Rolls.
Following the death of his son in 1762, the male line came to an end and the estates passed to his daughter Anne, the sole heiress, who married Michael Hill, of Hillsborough, County Down.
The estates then passed to their second son, Arthur Hill (d 1771) who, on succeeding to the lands in 1763, assumed the surname of Trevor.
Arthur Hill was created VISCOUNT DUNGANNON of the 2nd creation in 1765.
He was MP for Hillsborough, 1715-27; MP for County Down, 1727-65; Sheriff of County Down, 1736; a Privy Counsellor in 1750; Chancellor of the Exchequer [Ireland], 1754-55; Commissioner of Revenue [Ireland], 1755-71.
In 1759, his surname was legally changed to Hill-Trevor by Act of Parliament.
Arthur, 1st Viscount, was succeeded by his grandson,
ARTHUR [Hill-Trevor] (1763-1837), 2nd Viscount, whose son,
ARTHUR (1798-1862), 3rd Viscount, was the last of the male line and, on his death, the Brynkinalt and other estates devolved upon his kinsman,
LORD ARTHUR EDWIN HILL (1819-94), 1st Baron Trevor of Brynkinalt, 3rd son of Arthur, 3rd Marquess of Downshire, and great-grandson of Ann Trevor's elder son, Trevor Hill, 1st Viscount Hillsborough, the viscountcy of Dungannon having become extinct in 1862.
The estate and title then descended in the male to Charles Edwin Hill-Trevor (b 1928), 4th Baron Trevor.
The County Down seat of the Viscounts Dungannon was Belvoir Park at Newtownbreda, near Belfast.
First published in December, 2011. Dungannon arms courtesy of European Heraldry.