Henry is born on March 7, 1864 in Cahore, Draperstown, County Londonderry, the son of a prosperous Roman Catholic businessman. He is educated at Marist College, Dundalk, Mount St. Mary’s College, Chesterfield, Derbyshire (a Jesuit foundation) and Queen’s College, Belfast, where he wins every law scholarship available to a student in addition to many other prizes and exhibitions. In 1885, he is called to the Bar of Ireland.
During the 1895 United Kingdom general election campaign, Henry speaks in support of unionist candidates in two constituencies: Thomas Lea in South Londonderry, Henry’s native constituency, and E. T. Herdman in East Donegal.
Henry’s legal career flourishes. He becomes Queen’s Counsel in 1896, a Bencher of the King’s Inns in 1898 and ultimately Father of the North-West Circuit – but his interest in politics does not diminish. In March 1905, he is a delegate at the inaugural meeting of the Ulster Unionist Council and in the 1907 North Tyrone by-election he is the Unionist candidate, losing by a mere seven votes.
On May 23, 1916, Henry is elected as an MP in the South Londonderry by-election, the first by-election to be held in Ireland after the Easter Rising, which occurred a month earlier. The rebellion has had no discernible impact on the contest.
In November 1918, Henry becomes Solicitor-General for Ireland and in July 1919, Attorney-General for Ireland. He later serves as the first Lord Chief Justice of Northern Ireland from 1921 to 1925. In 1923, he becomes a Baronet, of Cahore in the County of Londonderry.
Henry marries Violet Holmes, daughter of Hugh Holmes, a judge of the Court of Appeal in Ireland, and Olivia Moule. They have five children, including James Holmes Henry, who succeeds as second baronet. It is a mixed marriage as Violet is and remains a staunch member of the Church of Ireland. Despite their religious differences, the marriage is said to be happy.
Henry dies in Belfast on October 1, 1925, aged 61, and is buried near his native Draperstown.
(Pictured: Sir Denis Stanislaus Henry, 1st Baronet, bromide print by Walter Stoneman, 1920, National Portrait Gallery, London)