Laurence O’Toole was born at Castledermot, Co Kildare in 1128 and died at Eu, Normandy, France, on 14 November 1180; and canonised in 1225 by Pope Honorius III. Born Lorcán Ua Tuathail, his mother was an O’Byrne and his father Murtagh or Maurice O’Tuathail, a Leinster chieftain of the Murrays – both sides were of princely stock. In the 2nd century, the Celt Tuathail was one of the great Irish kings. Another of the line reigned in 533. One of the seven churches of Glendalough, Co Wicklow, served as the burial site for many generations of O’Tuathails. O’Toole comes from Tuathal, meaning ruler of the people.

In 1162 Lorcán Ó Tuathail was elected, at the age of 32, the first Irish Archbishop of Dublin. At the time, Dublin was predominantly a Danish settlement. Previously Abbot of Glendalough, he set himself to reform church life in Dublin. One of his first acts was to begin building in stone the Cathedral of the Holy Trinity, now called Christ Church Cathedral. The Norman invasion of 1169 touched his family closely. Dermot MacMurrough, who in his attempt to regain the kingship of Leinster from which he had been deposed, invited a group of Norman knights to lend him military support, was Laurence’s brother-in-law. 

Laurence was notable for his talents as a peace-maker which made him acceptable to all elements in society. His election as archbishop had been supported not only by the Irish clergy but by the Danish and Norse groups and by Rory O’Connor, High King of Ireland. In partnership with Strongbow, leader of the Normans, he completed Christ Church Cathedral as a mark of reconciliation between the Irish, the Norse, and the Norman groups in the population. 

While on a mission to improve the relations between Henry II, King of England to whom had been conceded the title Lord of Ireland, and Rory O’Connor, High King of Ireland, he died at Eu in Normandy, in 1180.

His heart is venerated in a reliquary at Christ Church Cathedral, Dublin.