Queen in fits of giggles as formal facade slips

But that mask slipped at the Highland Games, when she became genuinely amused at events on the field.

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Laughing heartily, she shared the joke with the Duke of Edinburgh and the rest of the great and the good in the Royal pavilion.

It was certainly a change of mood from 24 hours earlier, when she had attended the solemn memorial service to mark the tenth anniversary of Princess Diana's death.

The Queen is patron of the Braemar Gathering in Aberdeenshire, which attracted 17,000 spectators to watch events including the caber toss and hammer throw and to listen to the Inverurie Pipe Band.

Prince Philip took a special interest in the tug-of-war, using his binoculars for a closer look and clapping vigorously as the Balmoral team triumphed.

Visitor Lucille Birne, from New York, said: "It was really great to see the Queen and Prince Philip, although it's a shame no other Royals were here. The gathering has a great buzz about it."

At the start of the event, the Queen was presented with a posy by 11-year-old William Marsden and, at the end, she handed out the awards - including a trophy to Bruce Aitken, who won the overall heavyweight competition for the ninth year in a row.

The Braemar Gathering coincides with the Queen's annual two-month break at Balmoral.