No-one seems to know the origin of the phrase "the luck of the Irish", or agree on its meaning. Is it really about good luck: shamrocks and the pot of gold at the end of the rainbow; or a bitterly ironic reference to the tragic events of Irish history, in other words, extremely bad luck?

"It's just one of those ghastly clichés," says Roy Foster, Carroll Professor of Irish History at Oxford. He had a specific reason for adapting it for the title of the short, eloquent book he has written about the extraordinary transformation of every aspect of public and private life in Ireland over the past 30 years: Luck and the Irish: A Brief History of Change 1970-2000.

He explains: "When I use the word luck' I don't mean something like chance' but more like the Latin fortuna - a favourable combination of circumstances.

"What nobody expected to happen was this huge wave of prosperity," he says. Moreover, no-one has been able to fully explain the economic miracle, although in the book he carefully analyses many of the contributing factors, including the close relationship between Ireland and the US; the country's entry into the EEC in 1973; and, paradoxically, its previous lack of development. "The sheer lack of accumulated industrial encumbrance enabled the Irish economy to leapfrog into the microelectronic age."

Talent, imagination and hard work all played a part, he says: "But I do still think there was an element of fortune."

In the second chapter, he considers another significant change: "the shattering of the Catholic Church's moral monopoly". He looks closely at the role that the women's movement played in this, remembering key moments in their struggle for equality and freedom, including the Contraception Train initiative of May 1971, when women from Ireland travelled en masse to Belfast to buy contraceptives, something the law prevented them from doing in the Republic.

He considers the growing importance of women in Irish political life, and the key contribution of President Mary Robinson, as well as recounting the rise and fall of the late former Taoiseach (Prime Minister) Charles Haughey with great gusto: "It was such a Balzacian story. But what struck me most forcibly was researching the chapter about what the North had done to politics and perceptions in the South during 30 years of mayhem. Partition became entrenched, not diluted. Ireland is now partitioned more strongly than ever."

One enjoyable aspect of the book is the author's use of unconventional sources, mixed in with material from government archives as well as sociological and statistical studies. These give vivid insights into the times about which he is writing, and include the Hello!-like celebrity magazine VIP; rock magazines such as Hot Press; people's personal memories; ephemera such as political pamphlets; and Bob Geldof's autobiography.

He looks at the importance of Ireland's "genius for advertising" to both its economy and cultural life. It was one of the first countries in the world to develop a coherent advertising strategy for itself: "Ireland's tourist image is very vivid and very widely disseminated and a lot of that is clever branding."

He examines the myths and clichés that cling to the Emerald Isle, and how these are sometimes manipulated, for example, through "the astonishingly fabricated notion of the Irish pub". Four companies run franchises in over 40 countries. "Now they are starting to appear in Ireland as well," he notes, dryly.

In this, as in his previous books (which include Modern Ireland, 1600-1972 and W B Yeats: A Life), he challenges such clichés. "Too much cultural analysis in Ireland seems either to wander down the track of mellifluous waffle or to fall back on crude old cowboys-and-Indians history."

The final chapter considers the recent renaissance of Irish literature, in particular the increasing importance of the novel in a country previously better-known for its short stories and poetry: "I think that has something to do with increasing confidence of ambition."

For several years he has been involved in the Ewart-Biggs Trust, set up in memory of Christopher Ewart-Biggs, the British Ambassador to Ireland who was assassinated by the IRA in Dublin in 1976. Its aim is to increase peace and understanding between the people of Britain and Ireland and it gives a biennial literature prize for writers whose work has contributed to this.

Prof Foster's personal perspective on Irish history comes from being born and brought up in Ireland, but having lived more than half his life in Britain, though he travels to Ireland frequently for work and holidays.

Because the book recounts such recent events, he admits that it raises some questions about what counts as history and what is "opinion, speculation and forecast". He enjoyed writing it, partly because it provided an opportunity to look back over his own life. "It's fascinating trying to remember what you expected to happen."

Luck and the Irish is published by Allen Lane at £20.