US president Barack Obama has visited the Queen at Windsor Castle the day after her 90th birthday.
The outgoing American leader and the First Lady Michelle Obama touched down in the grounds of the monarch's Berkshire home in the Marine One presidential helicopter, landing on the golf course.
The Obamas, who have a warm relationship with the Queen, are joining the sovereign and the Duke of Edinburgh for lunch in the castle's private dining room.
They were greeted by the monarch, who was dressed in a headscarf, and Philip, before shaking hands with the royal couple.
The 94-year-old Duke took on the responsibility of driving the Obamas the short distance to the castle himself - which Barack looked delighted about. He got behind the wheel of the Queen's Range Rover while Obama took his place in the passenger seat.
The First Lady joined the Queen in the back seats. As they set off they were followed by the president's 11 car motorcade for the brief journey.
Obama emerged from the green helicopter, which bears his presidential seal and a star and stripes flag on the side, and waved at his royal hosts.
Barack and Michelle Obama have developed a close bond with the Queen and her family, with the First Lady and the monarch striking up a firm friendship ahead of the G20 summit in 2009, where they were spotted with their arms around one another's back.
The nation's longest serving monarch, who celebrated her 90th yesterday with a birthday walkabout and a black tie dinner with her family, is seen as an important asset in maintaining Britain's close ties with the US.
This evening, the Obamas are dining with the Duke and Duchess of Cambridge and Prince Harry at Kensington Palace.