President Obama and his wife Michelle are attending a banquet given by Queen Elizabeth on the latest stage of his state visit to Britain. One hundred and seventy guests have been invited to the dinner at Buckingham Palace. Our correspondent Peter Hunt has followed the rest of the American president's

engagement

s which included several of London's famous sites.

After lunch, Barack and Michelle Obama went to Westminster Abbey. The president laid a wreath on the Grave of the Unknown Warrior. He also visited a secondary school with the Prime Minister David Cameron. They played table tennis with some teenagers; the two leaders lost. And tomorrow, the focus will

shift to

Downing Street and talks on a range of issues, including Afghanistan and Libya. By then, the pomp will have been replaced by politics.

Airlines have cancelled 500 flights in Scotland and northern England as a plume of volcanic ash spreads from Iceland. The International Air Transport Association criticised the British authorities for lacking test aircraft to monitor the cloud. The Irish airline Ryanair said there was no high-density ash over Scotland and accused Britain's Civil Aviation Authority of incompetence. Jonathan Astill from the air traffic control company Nats says conditions should improve in the next 12 hours.

"The higher-density volcanic ash clouds will continue to sit over the north of England, and then as we go through into the early hours of the morning, that ash cloud will start to disperse into the North Sea.