Barack Obama has described Britain's Prince George as "adorable" after Prince William and Kate Middleton's 2-year-old son was allowed to stay up past his bed-time to meet the US President.The two-year-old royal greeted him in his pyjamas and dressing gown at Kensington Palaceon Friday evening as the Duke and Duchess of Cambridge hosted the US President and First Lady. "I guess you all know why I came this week. It's no secret. Nothing was going to stop me from wishing happy birthday to her majesty, or meeting George, who was adorable," he told audience gathered for a town-hall style event in central London on Saturday.