Kings and queens from around the world have gathered in Britain to mark the Queen's Diamond Jubilee.
Twelve UK royals joined the Queen to welcome the sovereigns of 26 countries for a luncheon at Windsor Castle.
Human rights campaigners have condemned the inclusion of Bahrain's King Hamad al-Khalifa but the Palace said the Foreign Office approved his invitation.
Protesters gathered at Buckingham Palace, where Prince Charles is hosting a dinner for some of the royals.
King Hamad is not at the banquet.
Another invitation proving to be controversial is that of King Mswati III of Swaziland, who is accused of living a lavish lifestyle while his people go hungry.
Demonstrators at Buckingham Palace chanted and held banners reading: "Shame on you Liz Windsor," and "Democracy now for Swaziland".
King Constantine II of the Hellenes, King Michael of Romania, The Queen, King Simeon of Bulgaria and the Sultan of Brunei.
The Duke and Duchess of Cambridge and the King and Queen of Jordan.