Heavy rain and high river levels failed to disrupt the ancient ritual of swan counting on the River Thames.
The traditional count now serves a conservational purpose
David Barber, Her Majesty's Swan Marker, and his team of Swan Uppers began the population census on time.
Every year a flotilla of Thames rowing skiffs filled with scarlet-coated crews, sets sail on a week-long journey through Berkshire towards Oxfordshire.
The officials wear traditional uniforms and each boat flies appropriate flags and pennants.
A spokeswoman for the Swan Marker's office said: "Only a flood warning would put them off and we haven't had any of those so it is going ahead."
Their job is to corral, catch and mark all the unmarked, mute swans on the water between London and Abingdon in Oxfordshire, where they hope to arrive this Friday.
When a brood of cygnets is sighted, a cry of "All up!" is given to signal that the boats should get into position.
On passing Windsor Castle, the rowers stand to attention in their boats with oars raised and salute Her Majesty The Queen, Seigneur of the Swans.
The ceremony 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.
Today the Queen exercises this right only on certain stretches of the River Thames and surrounding tributaries.
Swan Upping, originally a kind of royal larder stock check, now serves a conservational rather culinary purpose.
The swans and cygnets are weighed, ringed and checked for signs of disease or injury.
Some swans are attacked by dogs, shot or hurt by fishing tackle every year and Swan Upping can assess how prevalent these problems are.