A TV star joined the historic Swan Upping this year, which includes the Marlow stretch of the River Thames.
Martin Clunes, of Doc Martin fame, boarded the boats alongside the Royal Swan Uppers, including the Queen's Swan Marker, David Barber.
The TV star was filming an ITV documentary series called Man and Beast, showing man's involvement with birds and animals the world over.
Mr Barber, who is in his 22nd year as the Queen's Swan Marker, said: "He was absolutely delightful. Hopefully they will make a very good programme."
Martin was on board the boats between Cookham Bridge and Marlow Lock on Tuesday, and appeared to enjoy every minute of it.
Fans had their photos taken with him when the boats stopped to assess the health of young cygnets and swans.
The Swan Upping lasts five days, starting at Sunbury and finishing at Abingdon Bridge tomorrow at 5pm.
Mr Barber said: "It has been going extremely well. The cygnet numbers are up slightly from last year, which is all very positive."
It is a tradition dating back to the 12th century- the Queen's Royal officials take to the waters in their skiffs to do the annual census of the swan population.
Back in the 12th century swans were highly prized for their meat and were served at banquets.
The monarch used to claim ownership of any unmarked mute swans swimming in open water.
In modern times, it has been about conservation. They 'up' any swans or cygnets they come across out of the water before weighing and assessing them for illness or injury.
It also involves the Queen’s Swan Warden collecting data.
Cygnets are extremely vulnerable at this early stage in their development and Swan Upping affords an opportunity to help both adults and cygnets that might otherwise go untreated.
Mr Barber said the flooding earlier in the year led to the death of some cygnets.
He said: "After the flooding has receded the river was running very fast. Some of the cygnets got washed over weirs, which is quite common.
"It is just one of those things.
"We have had a lot of dog attacks and shootings this year, which is more than we have ever had before.
"That is the idea of the education side- to try and help avoid all these sort of things- and for people to help look after the wildlife."
Anne Turk, 91, travelled from Bristol to Cookham to meet up with the Swan Uppers. Her grandfather, father and brother were all Keepers of the Swans - and she was the only lady Swan Upper ever