Britain's Prince William (second from left), Duke of Cambridge, and his wife Catherine (left), The Duchess of Cambridge, meet with the President of Singapore Tony Tan Keng Yam (second from right) and his wife Mary Chee Bee Kiang (right) at the Royal Garden Hotel in London, Britain, 21 October 2014, on the first of a four-day state visit.
The 88-year-old monarch and her husband Prince Philip paid state visits to Singapore in 1972, 1989 and 2006 but this is the first visit to Britain by a Singaporean president.
Tan lated visited Westminster Abbey to lay a wreath at the Grave of the Unknown Warrior, before touring the church and viewing the life-size marble memorial to Stamford Raffles, the statesman who founded the British colony of Singapore in 1819.
The president, 74, then visited parliament and delivered a speech in the royal robing room. Queen Elizabeth then welcomed Tan at a lavish state banquet of 170 guests at Buckingham Palace, making a speech noting the close relationship between the two Commonwealth countries.
"Looking back at half a century of co-operation and ahead to new chapters in our story, it is clear that our countries remain firm friends," the queen said, dressed in a cream gown and a tiara.
"I have no doubt that by maintaining long-standing commitments to openness, fairness and enterprise, this friendship will not only be sustained but will flourish and thrive."
Singapore gained independence from Britain in 1963 and immediately became part of Malaysia, which it then left in 1965.
Tan invited the queen to visit the country on its 50th anniversary celebrations in 2015, saying "the people of Singapore have genuine affection for Your Majesty."
"The friendship between our two countries has not only endured, but flourished," the president said.
William and Kate visited Singapore in 2012 as part of Queen Elizabeth's diamond jubilee celebrations marking her 60 years on the throne and as head of the Commonwealth.
Tan is due for talks with British Prime Minister David Cameron on Wednesday before wrapping up his visit on Friday. - AFP