US president Barack Obama last night rounded off his highly successful state visit to Britain by hosting a dinner in honour of the Queen.

The American leader and his wife Michelle staged the black-tie event for the monarch and the Duke of Edinburgh as a thank you for Tuesday's state banquet at Buckingham Palace.

More than 50 guests, including Mr Cameron and wife Samantha, Hollywood actor Tom Hanks, Oscar winner Colin Firth, England footballer David Beckham and Harry Potter author JK Rowling attended last night's dinner at Winfield House in Regent's Park, the official home of the US ambassador to Britain Louis Susman.

The Obamas waited on the mansion's doorstep for the arrival of the Queen and the Duke, where both couples greeted each other warmly.

The two heads of state led the way through the entrance of the residence, which serves a symbolic and political role and is the place where the leading figures from all walks of life are entertained by America's official representative in the UK.

Since arriving in London on Monday, Mr Obama has taken pains to reaffirm the special relationship between the UK and the US.

Yesterday, he addressed the "mother of parliaments" at the 900-year-old Westminster Hall, where he declared that both countries "stand squarely on the side of those who long to be free".

The US president rejected the argument that the rise of new economic powers such as China had sidelined Europe and America, insisting that "the time for our leadership is now".

At a "pivotal moment" in history, with demands for democracy across the Arab world and an international coalition fighting oppression in Libya, Britain and America remained "indispensable to the goal of a century which is more peaceful, more prosperous and more just", he said.

Earlier, he and Mr Cameron had held talks at 10 Downing Street. They pledged to "turn up the heat" on brutal authoritarian regimes, but they stressed they had "learned the lessons" from military adventures under Tony Blair and George W Bush.

The leaders also forged a special culinary relationship yesterday, rolling up their sleeves to jointly dish out burgers and sausages at a Downing Street barbecue for military families.

The two men served the cooked meat at a lunch party while their wives spooned side dishes on to guests' plates.