To get to the world's most exclusive lunch on Friday afternoon, you'll need to turn left at the McDonald's, slip behind the platoon of photographers, cut through the seething throng of angry people denouncing dictatorship, get X-rayed, leave your ermine at the coat check and then find your place on the most awkward seating plan ever devised.
And there, on the back lawn of Windsor Castle, will be a historic gathering of the 0.000001 per cent. Almost all of the world's reigning monarchs will be gathered at the home of the Queen as part of the Diamond Jubilee to celebrate her 60th year on the throne.
As dozens of kings, queens, emperors and empresses will be passing the port in the largest such gathering since 2002 (when the Queen Mother's funeral attracted a similar turnout), a crowd will be assembling outside – one that will likely express equal measures of reverence and rage.
For while the majority of the world's crown-wearers these days are constitutional monarchs – essentially head-of-state servants of elected parliaments – there will be a few old-fashioned absolutist rulers picking apart their poached salmon. The guests will likely have a few good items of gossip to share, including the empty place setting where the Spanish monarchs may have sat.
Queen Sofia and King Juan Carlos
Officially, Queen Sofia is boycotting the lunch in protest against the planned visit by Prince Edward, Queen Elizabeth's youngest son, to Gibraltar, the tiny British possession in the south of Spain. The Spanish claim possession of Gibraltar; the boycott marks a very high-level diplomatic snub.
But it may have more to do with King Juan Carlos's recent accident: He is bedridden, recovering from a serious hip fracture which was earned while elephant-hunting in Botswana. Spaniards, who are suffering under the continent's steepest unemployment rate, were hardly delighted by the idea of their ruler spending their money on elaborate holidays to hunt endangered species.
King Hamad bin Isa Al Khalifa
The largest throng of protests will be directing their ire at King Hamad, the Sunni monarch of Bahrain, who is accused of leading a vicious police and military crackdown against democracy protests by the tiny country's Shiite majority. His visit infuriates rights groups who feel he has blood on his hands
"Inviting blood-stained despots brings shame to our monarchy and tarnishes the Diamond Jubilee celebrations," British human-rights protester Peter Tatchell told reporters.
King Mswati III
Africa's "least popular leader," according to a poll this week, is facing an outright revolt from his people that appears to be unfolding in London as he visits. His hotel has been deluged with protesters, as Windsor Castle likely will be.
It should come as no surprise: King Mswati, who has 14 wives and lives an opulent life in one of the world's poorest countries, is one of the world's last truly absolute monarchs: He personally appoints the cabinet, the military and police heads, and the senior civil service.
King Abdullah bin Abdulaziz Al Saud
The Saudi king, while a near-absolute monarch without any significant democratic checks and balances, faces far more muted (or repressed) calls for democracy than the heads of his neighbouring Arab states. This is in large part because he spent $130-billion on extra handouts for his country's 27 million people, on top of his $800-billion, five-year stimulus program.
But King Abdullah's larger problem comes from within. His regime is absolutely geriatric: The very youngest qualified crown princes were born in the 1940s. The expected heir to the throne, Crown Prince Sultan bin Abdul-Aziz, died late last year in his 80s and there is no obvious line of succession.
King Carl XVI Gustaf
In spite of a very successful and crowd-pleasing royal marriage of his daughter Crown Princess Victoria in 2010 to a "commoner" (her personal trainer), King Gustaf's public popularity has slipped to an all-time low, and there's renewed talk of an elected head of state in Sweden. But he has been brought down by bling – he hasn't been able to escape public accounts of his racy private life, which include photographs showing him at strip clubs and accounts of close contacts with organized-crime characters.
Beatrix, the Dutch monarch, remains popular. But this is a tragic moment for her family. Her second son Prince Friso has been in a coma since February when an extreme-skiing accident in Austria led him to be trapped under an avalanche without oxygen for 50 minutes. He is unlikely to recover.
This has caused waves of grief and sympathy in the Netherlands – enough that people put aside a controversy ten years earlier when he married Mabel Wisse Smit, a commoner, and his royal succession was annulled by the Dutch Prime Minister when her earlier ties to a drug gang came to light.
Emperor Akihito and Empress Michiko
Japan's monarchy, like much of the country, is also falling prey to aging. Prince Akishino, the 78-year-old emperor's second youngest son, recently called for a "retirement age" for monarchs, after his father was released from hospital for a bout of pneumonia. There's been a deep rift between the two generations. The Emperor, who attended the Queen's coronation in 1953, is frail. He and his wife recently made a controversial public request for "cut-price funerals."