McLaughlin

The name is Mac Lochlainn, 'son of Lochlann', and Lochlann means Norseman or Scandinavian - the Viking lands. In Irish it still bends to its bearer: a son is Mac Lochlainn, a daughter Nic Lochlainn. Mc is only a contraction of Mac, sometimes cut again to M', so MacLaughlin, McLaughlin and M'Laughlin are one name, not three.

Not every Gaelic surname recorded a father; some recorded a people, and MacLachlainn meant son of a Scandinavian. A family at the head of the Uí Néill carrying a Norse name is no contradiction: the Vikings who settled Ireland from the 9th to the 11th centuries became wholly Gaelicised, and built its first towns.

The Mac Lochlainn belonged to the Cenél nEógain, senior branch of the Northern Uí Néill, who claimed descent from Niall Noígíallach, Niall of the Nine Hostages. The O'Neills were the chiefly family of that grouping; the MacLoughlins stood inside it. Their own seat was Inishowen in north-west Donegal, the peninsula between Loughs Foyle and Swilly.

Gaelic Ireland did not hand power to eldest sons. Under Brehon law a chief was elected by his kinsmen as custodian of the clan, the succession running by tanistry - the next chief chosen from the cousins of a shared grandfather. So being Cenél nEógain did not mean waiting your turn behind the O'Neills. It meant you could take it. For two generations, the Mac Lochlainn did.

The Uí Néill had lost the high kingship in 1002 to Brian Boru of the Dál gCais. Domhnall Mac Lochlainn, who died in 1121, made himself the dominant lord of the north by 1100 and was acknowledged High King of Ireland with opposition until his death - the annalists' careful formula for a supremacy real and recognised but never unchallenged. He had put the northern Uí Néill back at the summit of Ireland through his own line, not the O'Neills'.

His great-grandson Muircheartach Mac Lochlainn, who died in 1166, was the most powerful Irish king of the mid-12th century, ruling from Tír Eógain and binding most of Ulster, Connacht and Leinster into nominal submission. It ended at Leitir Lúin in 1166, where he was defeated and killed by Donnchadh Ó Cearbhaill of Airgialla. The vacuum he left was the opening Diarmait Mac Murchada exploited a year later, seeking help abroad and bringing back the Norman intervention of 1169. The knights who reshaped Ireland came through a door a Mac Lochlainn defeat had opened.

After 1166 the leadership of the Cenél nEógain reverted to the O'Neills and never came back. The Mac Lochlainn declined into a regional lordship in Inishowen - still chiefs of their own country, no longer makers of kings.

The order they belonged to was dismantled by law before it was broken by war. In the 16th century English common law was extended across Ireland, and the county and the sheriff replaced the chief and his country. From the founding of the Kingdom of Ireland in 1541 the chiefs were drawn in with new titles, while surrender and regrant swapped tanistry for primogeniture. In 1607 the senior chiefs of Ulster sailed for Spain to seek support, failed, and died in Rome. That Flight of the Earls cleared the way for the Plantation of Ulster, and the Mac Lochlainn lost their lands with the rest.

Most Irish surnames have one Gaelic source. McLaughlin has three. Besides Mac Lochlainn of Inishowen, the spelling also renders Ó Maoilsheachlainn, anglicised O'Melaghlin - the Clann Cholmáin of the Southern Uí Néill, descendants of Máel Sechnaill II, King of Meath from 976 to 1022 and himself High King of Ireland. More rarely it renders Ó Lachtna, or Loughney. From the English spelling alone a bearer cannot tell which of the three he descends from.

Nor was an Irish clan ever purely a bloodline: it took in unrelated clients of the chief, who assumed the leading lineage's name as a show of allegiance. The great genealogies, from Rawlinson B 502 to the Leabhar Mór na nGenealach, record the descent of chiefs, not of every member, and one genetic study judges them accurate only back to the Middle Ages. The tradition that the family also crossed the North Channel to become Clan MacLachlan sits in the same category: reported, plausible, unproven.

The surname stayed densest across Inishowen and the north-west, and left with the 19th-century Donegal, Derry and Antrim emigrations - to Pennsylvania, the Carolinas and the towns that became the Rust Belt, and to Glasgow and Liverpool. McLaughlin became the usual American form, McLoughlin the modern Irish one, and where the Mc was dropped the name survives as Loughlin. No name was ever legally changed at Ellis Island, whatever the family story says; the emigrants chose their own.

Ann McLaughlin Korologos was US Secretary of Labor from 1987 to 1989; Audrey McLaughlin led Canada's New Democratic Party; Donal McLaughlin designed the United Nations flag; John McLaughlin, a Doncaster violinist's son, taught himself the guitar, played on Miles Davis's In a Silent Way and Bitches Brew at the birth of jazz-rock fusion, and founded the Mahavishnu Orchestra. And in Donegal North East, the constituency that holds Inishowen, the family's own country has sent Pádraig Mac Lochlainn to parliament under the name in its original Irish.