The sale of Farmleigh, the Guinness family seat in Ireland, is a further unravelling of the ties between the family and this country. Paradoxically, it comes at a time when the "Guinness" and "Ireland" brands are practically synonymous and use each other to their mutual benefit to sell stout and tourism.
Although a spokesman for the family insisted that they will keep their connections with Ireland, Farmleigh is the last of what was once a string of great Guinness homes in this country. They included Iveagh House in St Stephen's Green (now the Department of Foreign Affairs), St Anne's in Clontarf (demolished in the 1940s and now the park of the same name), and Ashford Castle in Co Mayo (now a hotel).
Other members of the extended Guinness family, such as the Moyne branch to which Desmond Guinness belongs, continue to live in Ireland. But Farmleigh is the last home here of the main branch of the brewing family, the Iveaghs.
Ironically, their slow disengagement from Ireland began around the time that Edward Cecil Guinness - great-grandson of Arthur Guinness, the founder of the brewery and great-great-grandfather of the present Earl of Iveagh - bought Farmleigh in the 1870s. Around that time he bought out his brother, later Lord Ardilaun, and became the sole owner of what was fast becoming the largest brewery in the world.
Extremely ambitious, Edward floated the brewery on the stock exchange a decade later, receiving some £5.5 million while effectively retaining control of the public company. Using the usual factor of 50 to get a measure of late 19th-century values, that is roughly the equivalent of some £275 million today.
By that stage in the brewery's and family's development, Ireland was clearly becoming too small for them. They were far and away the richest family in the country. Indeed by the turn of the century Edward (then Lord Iveagh) was the third-richest man in the United Kingdom, according to the Sunday Times annual "rich list", which recently estimated his wealth then at almost £2 billion in today's values. They put him behind Cecil Rhodes (diamonds and gold) and the Wills family (tobacco) and well ahead of Rothschilds and the Duke of Westminster.
Part of the Guinness story, and why it emerged successful from among several hundred breweries in Dublin in the mid-18th century, has to do with the family's superb handling of the city's political and sectarian tensions. Politically-motivated commercial boycotts were not infrequent, but Guinness, an evangelical Protestant family reliant on mainly Catholic customers, managed to steer a careful path through that minefield.
They were occasionally accused by both sides of hypocrisy, but rode out the odd boycott by picking their causes and moderating their stances carefully. By the third quarter of the 19th century, however, the Home Rule movement had polarised opinion and narrowed the room for manoeuvre.
Edward Guinness and his brother, Lord Ardilaun, were both approached by Isaac Butt to join his Home Rule movement, indicating the contemporary view of them as political liberals. Ardilaun quickly made it clear, on behalf of both, however, that their loyalty was to queen and empire.
Edward's social ambitions and his desire for a title led him to contribute handsomely to the Conservative Party and to agree to stand for a Dublin constituency to try to halt the onward march of Parnell. He failed to get elected, but the titles eventually began to come, in response to private political contributions and public philanthropy.
Thus began a life of determined leisure, hunting, shooting and fishing in the Edwardian manner. In order to move into the upper classes he bought the 23,000-acre Elveden estate in Suffolk which he used purely for shooting. Farmleigh was still used during the Dublin "season", but Elveden became - and remains - the family's main seat.
The Guinnesses were never entirely sure whether they were Irish or English, or both. The late Lord Moyne, Bryan Guinness, illustrated the dilemma nicely in one of his memoirs. He recalled realising at some point in his childhood that one could be simply English: up to then he thought you had to be Irish-English (his own family) or Scottish-English (his nannies).
Edward, the first Earl of Iveagh, created the huge wealth on which his descendants more or less still live and which has underpinned the Guinness reputation in Britain for great wealth. The most recent Sunday Times "rich list" puts them at No 26 in the UK with an estimated value of £680 million.
In Ireland their reputation is more complex. People generally know little about the family - helped by its own desire for secrecy - and the connections between the numerous Guinnesses who flit in and out of social pages. The death of the first Lord Iveagh in 1927 was marked in Dublin newspapers by short and perfunctory obituaries.
While they maintained their reputation as good employers and philanthropists, their unionist politics left them out on a limb in independent Ireland, although they quickly adjusted to doing business with the new Free State.
In many respects they were the ultimate business pragmatists: the union was important to them because so much of their stout was sold in Britain and the empire. When a trade war threatened in the 1930s they finally activated plans that had been drawn up when Home Rule looked likely before the first World War and moved their headquarters to England.
The third Earl, Benjamin, briefly reversed the process in the 1970s when he moved the family back to Farmleigh, where two of his children were born, and accepted a nomination to the Seanad from the Taoiseach, Liam Cosgrave. The sale of the house by his executors and trustees marks the end of that development.
According to Robin Howard, chief executive of the Iveagh Trustees, the present generation of Guinnesses, two men and two women, may now buy other properties in Ireland to maintain their connection with the country. The family still retains a property link in Ireland through its 700-acre farm at Kilrue, Co Meath.
But the sale of Farmleigh is the end of an era for the family which created Ireland's greatest international brand name. Tourists who buy Guinness souvenirs and visit the brewery museum in Dublin and foreigners who drink Guinness in Irish pubs abroad don't care that the stout is the product of a conglomerate with a made-up name, Diageo.
To them, Guinness is Ireland.