In Peace in Ireland, his recent book on the Northern Irish Troubles, Richard Bourke tells a revealing story about Richard Crossman, secretary of state for social services during Harold Wilson's government of 1966-70. Referring to riots that had occurred at the Orange parades of 12 July 1969, Crossman wrote in his diary: "There had been commotions on St Patrick's Day, it may have been."
Although Northern Ireland no longer poses quite such a challenge, today's ministers would do well to have a firmer grasp of the local parade calender than Crossman. Keeping The Encyclopaedia of Ireland to hand might help. The general editor, Brian Lalor, acknowledges the difficulty of deciding what to leave in or leave out. Its aim is "to celebrate the gift to the culture of the world of a vibrant and irrepressible people". And in a pre-publication interview he said: "In the past there was an assertion to be made about Irishness: we don't need to make that now."
Certainly, several of the entries here disregard birthplace: Richard Ellmann, from Michigan, is included as the main authority on Irish modernists. Other entries are surprising because they acknowledge the Irishness of figures who could so easily be brushed out of the history, such as General Dyer, the colonial enforcer responsible for the Amritsar massacre in 1919.
Over the past decade, Ireland has become richer than at any previous time in its history. Between 1995 and 2000 its economic output increased by more than 50 per cent and its population increased by almost half a million. In 1968, at a time of less spectacular economic growth, a more modest Encyclopaedia of Ireland was published. I remember the iconic place it had on the shelf in our village primary school. Its black-and-white pictures conveyed an impression of dynamism: new hospitals, new schools, helicopters landing on lighthouses. The text heralded "a new spirit of tolerance" in religion and politics, "ever-increasing opportunity" in education, "truly remarkable" economic growth and a "fresh awakening" in the arts.
The same tone is partly evident in this vastly more comprehensive new version, although there are striking differences, most notably in the entries on the Catholic Church. The 1968 edition defended the clause in the Irish constitution granting special status to the Catholic faith by declaring that "the church of so great a majority must hold some kind of special position in a democratic state". By 2003 the Church's status is all but demolished: "Though Ireland still has one of the highest rates of religious practice in Europe, the lack of vocations to the priesthood and religious life and the inability of the church to appeal to the mass of younger people, coupled with increasing secularisation, means that Irish Catholicism must respond with greater elan than its contemporary complacency exhibits if it is to have any significant future."
Most of the entries are not as penetrating as this. You wish that some were, or at least that they were longer than some others. Do we need to be told when the waltz was introduced to Ireland or about the poems on the Dart train in Dublin? And there are surprising omissions: the novelist Eoin McNamee; the playwright Vincent Woods; or Douglas Gageby, the man largely responsible for turning the Irish Times, once Ireland's unionist paper, into the bible of the Catholic middle classes.
Overall, however, The Encyclopaedia of Ireland is a delight to consult and a valuable gateway to other reading. As well as distinguishing between 12 July and St Patrick's Day, Crossman's successors in Whitehall will be able to discover that "The Teddy Bears' Picnic" was written by an Irishman, and to marvel at the practice of ether-drinking that flourished in the late 19th century: "The pulse quickens, the face flushes, and a wave of excitement is followed by visions, perhaps of dancing on clouds to heavenly music . . ."
Maurice Walsh is a BBC journalist. He is completing a study of foreign correspondents who reported on the Irish revolution