A photo posted by Kensington Palace on its official instagram account shows Prince George meeting US President Barack Obama and his wife Michelle in his pajamas on Friday evening. [Photo:/kensingtonroyal instagram]

The UK's Prince George met US President Barack Obama and his wife Michelle in his pajamas on Friday evening as his mother and father hosted the US President and the first lady at Kensington Palace in London.

The two-year-old prince, wrapped up in a white dressing gown just before bedtime, showed the couple his rocking horse.

Obama and his wife Michelle plunged into a whirlwind of royal socialising on Friday that began over a birthday lunch with Queen Elizabeth II and ended at a dinner hosted by the trio of young royals - Prince William, Kate, Duchess of Cambridge, and Prince Harry - who represent the future of the British monarchy.