Ronald Reagan's radical conservatism changed the United States and the world during his two terms in office as President from 1981-89. He set an agenda of conviction politics, direct political communication, tax cutting, trickle-down economics, hostility to big government, opposition to trade union power and the assertive use of US military strength abroad which influenced many other leaders - not least Mrs Margaret Thatcher, whose time in office overlapped so closely with his.
Mr Reagan's acting and film background gave him an insight into communication, which proved of enormous benefit when he turned to a political career as governor of California. He combined this skill with a natural and humorous personality and a conviction that political issues are capable of being tackled head on. Such virtues outweighed his supposed intellectual shortcomings and his reliance on ideological advisers, who often acted without sufficient political accountability. He had little difficulty winning a second term in office, and his reputation has grown with the passing years, for most of which he was afflicted with Alzheimer's Disease.
While President George Bush snr differed in important respects from President Reagan, when he succeeded him there was a fundamental continuity in their policies. Mr Bush's most important achievement - managing the end of the Cold War and the collapse of the Soviet Union in 1989-91 - dealt in good part with the consequences of Mr Reagan's own effective anti-communist approach. Mr Bill Clinton's more centrist domestic policies during the 1990s accepted several fundamental premises established during the Reagan years - just as Mrs Thatcher's greatest legacy is said to be New Labour in Britain.
It is one thing to acknowledge Mr Reagan's political and historical achievements, quite another to endorse all his policy positions. Alongside his firm opposition to Soviet power there was a dangerous ratcheting up of military tension in Europe, subversion of change in Central America, growing support for expansionist Israeli policies in the Middle East and backing for Iraq in its war against Iran. At home Mr Reagan rhetorically opposed the big spending state, but left a legacy of huge budget deficits from bloated military spending. Those at the bottom of the social pile suffered from cuts in taxation and redistribution of resources to the rich.
Mr Reagan took a sympathetic interest in Ireland, arising from his own background and a shrewd realisation that his social conservatism appealed to many Irish-American Democrat voters. He played a significant role behind the scenes in convincing Mrs Thatcher to accept the Anglo-Irish Agreement in 1985, which laid the basis for the 1990s peace process. His period in office coincided with maturing business and professional achievements of Irish-Americans, their renewed identification with Ireland and securing access for young Irish people seeking work in the US. These features are as important as those of the Kennedy era in the early 1960s.