President Barack Obama plunged into a whirlwind of socializing Friday that began over a birthday lunch with Queen Elizabeth II and was ending at a dinner hosted by the trio of young royals who represent the future of the British monarchy.
Obama, accompanied by his wife, Michelle, arrived by helicopter on the verdant grounds of Windsor Castle, the sprawling, centuries-old royal residence and tourist lure located just west of London where the queen celebrated her 90th birthday a day earlier.
With a patterned scarf tied around her head in a light drizzle, the queen climbed from the dark blue Range Rover that her husband, Prince Philip, drove to the landing area, and Britain's oldest and longest-serving monarch welcomed her third American president to the castle.
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The couples exchanged handshakes before climbing into the vehicle — ladies in the back seat — for the short ride to the castle.
"I've never been driven by a Duke of Edinburgh before, and I can say it was a smooth ride," Obama said at an afternoon news conference.
Inside, the queen led the group into a sitting room warmed by a fire and asked the president where he wanted to sit. Obama was also expected to have dinner with the queen's grandsons later Friday.
The queen donned a periwinkle blue suit for the private lunch while Mrs. Obama wore an Oscar de la Renta print dress topped with a dark purple Narciso Rodriguez coat. The Obamas brought a gift in a box wrapped in gold paper and embossed with the presidential seal: a photo diary of the queen's many visits with U.S. presidents and first ladies. The album opens with her 1951 visit when, as Princess Elizabeth, Duchess of Edinburgh, she toured George Washington's estate at Mount Vernon in Virginia and met President Harry Truman at the White House.
She has not visited Obama at the White House.
Obama was capping the evening with a trip to Kensington Palace, where he and the first lady were invited for dinner with Prince William, his wife, Kate, and his brother, Prince Harry. William is second in line to ascend to the throne after his father, Prince Charles.
The series of royal engagements made up the centerpiece of Obama's three-day, valedictory trip to London, which was filled with multiple helicopter lifts and his lengthy motorcade winding its way through the city's narrow and winding streets.
Obama broke up the royal holiday by stopping at 10 Downing St. for private talks with Prime Minister David Cameron about the Islamic State group, Afghanistan, Syria, Libya, the global economy, Russia's stance toward Ukraine, politics and other issues.
They also discussed Britain's possible exit from the European Union, or Brexit, which Obama opposes, as well as the U.S. presidential campaign that will determine Obama's successor.
At a news conference following the meeting, Obama and Cameron touted the close alliance between the U.S. and Britain as "one of the strongest and longest the world has ever known."
Obama said the UK leaving the EU would send them to the back of the trade agreement queue because the main priority to the U.S. economy is to secure an agreement with the larger bloc versus a single nation.
Cameron noted the EU-U.S. trade agreement currently being negotiated and considered the largest in the world, was an effort led by Britain. "We set the agenda for talks," he said.
Cameron is leading the campaign in favor of Britain's continued membership in the 28-nation EU and wants Obama to speak out against leaving.
"Let me be clear, ultimately this is something that British voters have two decide for themselves," Obama said when asked about criticism from some that he is intervening in British politics. "But, part of being friends is to be honest. And speaking honestly, the outcome effects our prospects as well. The UK is at its best when it's leading a strong Europe."
Voters will have the final say in a June 23 referendum. Cameron faces opposition from within his Conservative government and widespread skepticism among voters about the benefits of continuing in the EU. Backers of those who support Britain's exit have accused Obama of hypocrisy and meddling.
In an opinion piece published online Thursday by the Daily Telegraph newspaper, Obama urges Britons to stay in the EU. He noted the decision will affect U.S. interests and said EU membership will magnify British influence inside and outside of Europe.
Obama's criticism of Cameron in an interview published recently in The Atlantic magazine could also come up. Obama faulted Cameron and other European allies for shortcomings in the handling of Libya after the 2011 toppling of leader Moammar Gadhafi. Obama said Cameron had become "distracted" by other issues. Libya has since descended into chaos and become a haven for members of the Islamic State group.
Obama and his family have enjoyed a series of engagements with the British royal family since he took office in 2009, including his first meeting with the queen that year. After the appointment, Obama said she was "delightful" and reminiscent of his grandmother.
The queen also welcomed Obama on a state visit in 2011 that included an overnight at Buckingham Palace.
"Each time, the president has come away with an even deeper personal affection for her," said Obama spokesman Josh Earnest. "She is an important symbol of a country with whom the United States has a special relationship. But she also is a human being whose charisma and a sense of nobility and honor is something that I think people around the world are attracted to."
The 2009 meeting is also where the queen and the much-taller Mrs. Obama showed how quickly they took a liking to each other by briefly standing arm in arm at a palace reception for participants at an economic summit in London. The queen strayed from protocol by wrapping an arm around the first lady, who reciprocated.
A palace spokesman at the time described the scene at the ladies' first meeting as a "mutual and spontaneous display of affection."