The count, with an 800 year old history, documents any unmarked mute swan for the Queen who owns every single one found on the Thames’s open water.
Boatmen in traditional scarlet coats set off from a London suburb for the week-long journey that also includes weighing the birds.
"Swan Upping" began from the 12th century when the crown claimed all of the unowned mute swans in England for its banquets and feasts and although they no longer grace the royal dining table the birds are still being counted for conservation purposes.