The King of Bahrain, whose regime has been accused of brutally suppressing pro-democracy demonstrations, joined the Queen for lunch at WIndsor Castle today to celebrate her Diamond Jubilee.
ITV News Royal Correspondent Tim Ewart:
The Middle East ruler is one of a number of foreign monarchs criticised for their human rights records or extravagant lifestyles who have been invited to dine with the British Royal Family.
Buckingham Palace has released a guest list for the Sovereign Monarchs lunch being held at Windsor Castle today - the biggest gathering of foreign royals in the UK since the Duke and Duchess of Cambridge's wedding last year.
Bahrain's King Hamad Al-Khalifa has been condemned as a despot by former Foreign Office minister Denis MacShane in the run up to the lunch. The Labour MP said many would regret Foreign Secretary William Hague's decision to approve the inclusion of the Middle East ruler.
But the Foreign Office has stressed it is supporting Bahrain in its attempts to improve its human rights and that it can achieve more by maintaining channels of communication with the country.
Guests from controversial regimes include Swaziland's King Mswati III, Sheikh Nasser Mohamed Al-Jaber Al-Sabah of Kuwait and Prince Mohammed Bin Nawaf Bin Abdulaziz Al Saud of Saudi Arabia.
Swaziland's King Mswati III, is accused of having a lavish lifestyle while his people starve.Protests were held outside the African ruler's exclusive London hotel earlier this week where he is said to be staying with an entourage of more than 30 people.
Recent reports by Amnesty International highlighted a wave of repression in Saudi Arabia as the authorities have cracked down on protesters and reformists.
The guest list also includes many members of European royalty including the Prince Albert II and Princess Charlene of Monaco, King Carl XVI Gustaf and Queen Silvia of Sweden and King Harald V and Queen Sonja of Norway.
But Queen Sophia of Spain is missing as she was ordered by her government to turn down the invitation.
The last minute snub was in response to a reported trip the Earl of Wessex will make to Gibraltar, a UK overseas territory which Spain wants returned to its sovereignty.
Members of the British monarchy attending the lunch include the Duke of Edinburgh, Duke and Duchess of Cambridge, Prince Harry, the Duke of York and Princesses Beatrice and Eugenie and the Earl and Countess of Wessex.