World's royals gather for Queen Elizabeth II's Diamond Jubilee lunch

Britain's Queen Elizabeth II (R) greet Emperor Akihito (2nd L) and Empress Michiko (L) of Japan at Windsor Castle, west of London, on May 18, 2012, during a Sovereign's Jubilee Lunch hosted by Britain's Queen Elizabeth II. A glittering lunch for the world's sovereigns to be held on Friday to celebrate the diamond jubilee of Britain's Queen Elizabeth II has been marked by a withdrawal and protests over the guest list. AFP PHOTO / ARTHUR EDWARDS/POOL (Photo credit should read ARTHUR EDWARDS/AFP/GettyImages)
Britain's Queen Elizabeth II (front row, sixth left) poses for a formal picture with her royal guests before a Sovereign Monarchs Jubilee lunch at Windsor Castle, west of London, on May 18, 2012.

(CBS/AP) LONDON - Royals from around the world gathered in London on Friday to celebrate Queen Elizabeth II's Diamond Jubilee.

The lunch in Windsor Castle was the largest gathering of foreign royals in Britain since the monarch's grandson, Prince William, married the former Kate Middleton last year.

Complete Coverage: Queen Elizabeth II's Diamond Jubilee

According to the Telegraph, the queen and her husband, Prince Philip, Duke of Edinburgh, greeted their guests personally when they arrived, waiting outside the castle's Waterloo Chamber, where the reception was held.

Some 45 royal guests from around the world were in attendance, including ones from Japan, Monaco, Denmark, Jordan, Thailand, Malaysia, Kuwait, Bulgaria, Luxembourg, Norway, Sweden, Romania, Morocco, Saudi Arabia, Qatar, Kuwait, Denmark and the Netherlands.

William and Kate, Duchess of Cambridge, also attended the lunch, as did Prince Harry, Prince Andrew and his daughters, Princess Beatrice and Princess Eugenie.

But others on the guest list have raised some eyebrows. Britain has come under criticism for inviting the king of Bahrain, whose Gulf state has been engaged in a brutal crackdown on political dissent.

The decision to extend an invitation to members of the Bahraini royal family (which was also done for William and Kate's wedding) has angered those who are upset by the deadly violence deployed against demonstrators since protests erupted in the Gulf state.

Bahrain's Crown Prince Salman bin Hamad Al Khalifa eventually skipped the royal wedding, saying he didn't want the controversy to tarnish the couple's happy day. But on Friday, Buckingham Palace confirmed that his father, King Hamad bin Isa Al Khalifa, attended the queen's lunch.

Al Khalifa wasn't the only controversial guest dining at Windsor Castle. Swaziland's King Mswati III, who is accused of living in luxury while his people go hungry, also is attending the lunch. Earlier this week protesters gathered outside the exclusive London hotel where he was rumored to be staying with a large entourage.

There wasn't anything in the way of protest outside Windsor Castle Friday. Sky News television footage showed a handful of royal supporters clutching red-and-white Bahraini flags.

Another royal was notable for her absence - Queen Sofia of Spain. She cancelled her visit to London earlier this week amid fresh disagreements over Gibraltar, the disputed British colony on Spain's southern tip.

An evening reception for the queen and her royal guests will reportedly take place at Buckingham Palace on Friday, hosted by Prince Charles. The king of Bahrain will not attend that event, the Telegraph reports.

The Diamond Jubilee marks 60 years of Elizabeth's reign as Britain's monarch.