Prince William and the Duchess of Cambridge welcomed Barack Obama to Buckingham Palace in their first major engagement as a Royal couple.
Fresh from their Seychelles honeymoon, the newlyweds spoke to the US President and his wife Michelle in a 10-minute private meeting.
There were smiles all round moments earlier when the Obamas arrived at Buckingham Palace and were met by the Queen and Prince Philip.
The Obamas, who arrived half a day ahead of schedule to avoid any disruption from the volcanic ash cloud, laid a wreath on the Tomb of the Unknown Warrior in Westminster Abbey and attended a state banquet at Buckingham Palace.
The president flew into Stansted, in Essex, with wife Michelle after leaving the Republic of Ireland, where his week-long tour of Europe began. They spent the night at the US ambassador’s residence Winfield House, in London’s Regent’s Park.
The state visit – only the third by a US president to the UK in 100 years – comes at a time of close co-operation between Britain and America on issues ranging from Libya to Afghanistan, counter-terrorism and the Middle East peace process.
After he was welcomed there by Prince Charles and his wife, the president’s cavalcade made its way to Buckingham Palace where he joined the Queen.
The Obamas met Prince and Princess William before moving to the palace gardens for a ceremonial welcome on the lawn of Buckingham Palace, followed by a private lunch with the Queen.
Security is tight during the three-day trip which comes ahead of the G8 summit of world leaders in France.
In the evening they attended a state banquet at Buckingham Palace, where they stayed overnight.
On Wednesday Obama is meeting Prime Minister David Cameron for talks.
There will be a news conference, before the president departs for the Houses of Parliament, where he will give a speech about US foreign policy to MPs in Westminster Hall.
The visit will end with a return banquet at Winfield House, where the Queen will say farewell.
Also in London, City.Mobi is celebrating the success of its new guide to London.
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City.Mobi guides include user reviews and traveller utilities such as a translation guide, currency converter, news and local weather guide.