The Queen watches her swans being counted on the River Thames.
The Queen has seen the ancient ritual of her swans being counted on the River Thames for the first time.
She may own all unmarked mute swans in open water in Britain, but she has never before watched the royal custom of Swan Upping in person.
The Queen went by boat from Boveney Lock at Eton Wick to Oakley Court flanked by a flotilla of skiffs to see cygnets being weighed and measured.
The week-long annual census will finish in Abingdon in Oxfordshire.
James Fletcher, BBC News, in Eton Wick
With the sun shining brightly at Boveney Lock, the Queen's Swan Uppers, dressed in matching red blazers and caps, formed an honour guard with their oars pointing skyward. Top concern for the small but expectant crowd was what Her Majesty would wear. As she arrived, an approving murmur went round "apricot."
The Queen then boarded an old-fashioned steamboat, gave a crowd-pleasing wave, and headed off upstream to follow the Swan Uppers. First stop was one of the idyllic green lawns that line the river, where a small group of school children waited for a demonstration of what the Swan Uppers will be doing all week - weighing and checking the health of the swans.
For the Royal performance though nothing was left to chance - the swans weren't caught in the river, but magically appeared from the riverside in the arms of the oarsmen.
Organisers changed the usual starting point in Sunbury in Surrey to the Berkshire-Buckinghamshire border in order to fit in the Queen's visit.
Her majesty, who is known as the Seigneur Of The Swans during the historic ceremony, met the team of Swan Uppers whose job it is to corral, catch and mark the swans.
When a brood of cygnets is sighted, a cry of "All up" is given to signal that the boats should get into position.
The swans - usually two parent birds and three cygnets - are then weighed, ringed and checked for signs of disease or injury.
The annual event dates back to the 12th Century when the ownership of all unowned mute swans in Britain was claimed by the Crown in order to ensure a ready supply for banquets and feasts.
Swan Upping now serves a conservational rather than culinary purpose.
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