During an official welcome ceremony on the White House lawn on Monday, Mr Bush stumbled over a line in his speech, initially saying the Queen had helped celebrate the US bicentennial in 1776, rather than 1976.

Realising his mistake, he winked broadly at the monarch before turning back to the assembled dignitaries to say: "She gave me a look that only a mother could give a child."

At a formal dinner last night at the British ambassador's residence in Washington, the Queen opened her speech with a toast to the US president.

Grinning playfully, she began: "I wondered whether I should start this toast by saying, 'When I was here in 1776...'" The guests, including Mr Bush, erupted in laughter.

In his own speech, the president responded: "Your Majesty, I can't top that one."

Away from the mutual ribbing, and on the day devolved government returned to Northern Ireland, the Queen thanked Mr Bush for previous US efforts in helping to bring peace to the region.

A few hours after the dinner, the 81-year-old monarch and Prince Philip flew home to Britain, ending the first state visit to the US for 16 years.

The six-day east coast tour also saw the Queen attend the Kentucky Derby and meet survivors of the Virginia Tech gun massacre.