This week's visit to Ireland by Queen Elizabeth II was remarkable. It was the first visit by a British monarch to the republic since Irish independence. It marked the transformation in relationships in these islands since the peace process started in the 1990s. But above all, it was a triumph for the Queen - and for another remarkable woman, Ireland's president, Mary McAleese.
Symbols matter in British-Irish relations, and the Queen played on this to huge effect. She wore Ireland's colour, green, when she arrived on Tuesday. She spoke in Irish at a banquet at Dublin castle (once the heart of British rule in Ireland). And Britain's queen bowed her head in respect to the garden of remembrance to Ireland's freedom fighters.
By most accounts, Ireland was impressed. That shouldn't be a surprise: relations between Britain and Ireland are as good as they've ever been. We live together, work together and no longer fear republican or loyalist bombs. The people of these islands have been quicker than the politicians to embrace each other. True, Sinn Féin and the DUP have gained ascendancy over more moderate rivals in the north. But they're also in government together - an idea as unthinkable even 10 years ago as the Queen's visit to the republic.
Sinn Féin was opposed to the Queen's visit - hardly a surprise, as the party relies on antipathy to Britain. Its president, Gerry Adams, insisted in defying accuracy by calling Elizabeth II 'England's Queen'. (There's no such thing as a 'queen of England'.) But the success of the visit put Adams on the back foot. Comically, he told a BBC interviewer that "I'm not a monarchist, in fact I'm a republican". Good of him to solve that mystery...
The Queen's visit prompts us to ponder the complicated relationship between the various countries in Great Britain and Ireland. In school in Wales in the 1970s, as the Troubles were killing thousands of innocent people on both sides of the Irish Sea, I studied the failure of 19th century British Liberal Governments to give 'home rule' to Ireland. I was convinced that the story of Britain and Ireland would have been very different had the English establishment not stupidly blocked home rule in 1886 and after. By the time a home rule act was passed by the British parliament in 1914, the combination of a treasonous rebellion by Ulster's unionists and the great war killed any chance of a sensible compromise. Fast forward to the present, and home rule (or devolution as it's now called) is established in Great Britain. No one knows if it will lead to the break up of Britain. I doubt it - but at least change is now through the ballot box rather than the bullet and bomb.
A final thought. The Queen who visited the republic this week isn't just Britain's Queen. She's Queen of Canada, Australia, New Zealand and 13 other territories. It's an extraordinary legacy of the past that Britain's head of state performs the same role for so many other countries. Ireland understandably decided in 1949 that it wanted its own head of state. Its most recent presidents, Mary Robinson and Mary McAleese, have been hugely popular and successful role models for a republican system, unlike Ireland's recent taoisigh (prime ministers). But Queen Elizabeth this week reminded us that constitutional monarchs can also achieve remarkable things.