Almost all the world's monarchs attend Jubilee Luncheon at Windsor Castle. The Spanish government balked at sending Queen Sophia due the the ongoing dispute over the island of Gibraltar. William and Catherine were there; as well as Princess Charlene
hellomagazine
Year of succession
1945: Thailand: King Bhumibol Adulyadej
1952 United Kingdom: Queen Elizabeth II
1977 Brunei: Sultan Hassanal Bolkiah
1970 Oman: Sultan Qaboos bin Said
1972 Denmark: Queen Margrethe
1973 Sweden: King Carl Gustaf
1980 Netherlands: Queen Beatrix
1986 Swaziland: King Mswati III
1989 Japan: Emperor Akihito
1989 Liechtenstein: Prince Hans-Adam II
1991 Norway: King Harald V
1993 Belgium: King Albert II
1995 Qatar: Emir Hamad bin Khalifa
1996 Lesotho: King Letsie III
1999 Bahrain: King Hamad bin Isa Al Khalifa
1999 Jordan: King Abdullah II
1999 Morocco: King Mohammed VI
2000 Luxembourg: Grand Duke Henri
2004 Cambodia: King Norodom Sihamoni
2005 Saudi Arabia: King Abdullah bin Abdul'aziz
2005 Monaco: Prince Albert II
2006 Bhutan: King Jigme Khesar Namgyel
2006 Kuwait: Emir Sabah al-Ahmad
2011 Malaysia: King Abdul Halim
2012 Tonga: King Tupou VI