It was supposed to be a celebration filled with regal splendour to herald the start of the Queen's Diamond Jubilee celebrations. But even before the poached eggs and noisettes of lamb were served, a row was raging over Britain's decision to invite a string of controversial, unelected monarchs.
The autocratic leaders of Bahrain and Swaziland, a prominent Saudi Arabian Prince and the heir to the throne of Thailand were among those taking their places for the "Monarchs' Lunch" at Windsor Castle. The Foreign Office said invitations to the lunch and a dinner at Buckingham Palace were sent to all of the world's sovereigns.
But the Queen was criticised for allowing some of the more contentious royals to dine with her. The most controversial person on the guest list was King Hamad bin Isa al-Khalifa of Bahrain. Human rights groups have condemned his regime for its slow pace of reform and politicised trials that have taken place since protests against his family's rule broke out last year, in which more than 60 people died. Only this week, new claims emerged suggesting that a young Bahraini found dead this year may have been tortured.
An official report into the death of Yousef Mowali, 23, in January said he had drowned in the sea. But a second autopsy published this week by an independent pathologist from Turkey reported that Mowali may have been electrocuted and was unconscious when he drowned.
Eyebrows were also raised at the inclusion of King Mswati III of impoverished Swaziland, whose retinue stayed in the £400-a-night ($837) Savoy hotel.
Although the Thai monarchy heads a constitutional democracy like Britain's, the invitation to Crown Prince Vajiralongkorn came at a time of renewed debate over the country's strict lese majeste laws. A 61-year-old man who was sentenced to 20 years' for sending offensive text messages about Queen Sirikit died in jail this month.
Opposition politicians in Bahrain said King Hamad's invitation to Windsor Castle sent out worrying signals that Britain was normalising relations with the Gulf kingdom, despite continued violence and dissatisfaction at the slow pace of promised reforms.
"This invitation is a gift to the regime and hardliners," said Matar Ebrahim, of the al-Wefaq party. "It will be the moderates and those who want to see reforms take place who will suffer. The British seemed to have reached the conclusion that they don't need the Bahraini people, just the Khalifa regime."