But at a ceremony on Monday in the suitably traditional upper-crust surroundings of Claridge's Hotel, London, the international creme de la creme will be able to raise a toast in their own honour once more.
Their pedigrees have been compiled for the first time in 54 years for a new edition of the 235-year-old Almanac de Gotha, which was once the social bible for the monarchies of the world.
The 671-page volume will be in English for the first time, as the authors believe the language has superseded French as the "traditional diplomatic tongue". For the blue-blooded, the importance of the almanac should not be under-estimated. When Princess Alexandra of Greece met her future husband, King Peter II of Yugoslavia, she asked: "But how are we related?" It is claimed her mother responded with a copy of the book.
Royalty magazine observed this month: "The Almanac de Gotha ... is the last and undisputed word on who is who. The royal libraries of Europe have been stocked with its editions since 1763. It is the nearest thing to a trades union when it comes to settling questions or disputes." The almanac had been owned and published by the Perthes family of the tiny Duchy of Saxe-Coburg and Gotha, until it became a nationalised asset of the former GDR.
In the wake of the reunification of Germany, the family, under Stephan Perthes, has resumed its various publishing interests, but decided against updating 50 years of royal births and deaths itself.
Charlotte Pike, 38, a former Burke's Peerage researcher, and John Kennedy, 32, a former private secretary to Prince Michael of Kent, took over the task.
After half a century without publication, Prince Charles as well as his sons William and Harry, will be among the royals taking their place in the volume for the first time. Others will include Maya Flick, the divorced wife of Mercedes heir Friedrich Flick, and her sister, Princess Gloria von Thurn und Taxis, dubbed the "Punk Princess". They are both members of the Schonburg-Glauchau family.
Belgrade-born John Kennedy may be regarded as having a personal interest. Described as a distant kinsman of the exiled Yugoslav royal family, he helped arrange a high-profile visit to Belgrade by exiled members of the family in 1991.
In 1992, Mr Kennedy, who has stood for Parliament for the Conservatives, was hailed as the "Kissinger of Yugoslavia" by Radovan Karadzic, leader of the Bosnian Serbs, for his peace efforts in the Bosnian conflict.
Copies of the earlier editions of the almanac still exist. The central reference library in Westminster, London, has many volumes from between 1775 and 1941, although not the last, published in 1944. A spokesman said: "It is used, on and off, mainly for historical research. There's fascinating stuff in there."Reuse content