The sheep were trained to handle big crowds and city traffic
Some 500 freemen have exercised their medieval right to drive sheep across London Bridge to raise charity funds.
A herd of 15 Romney ewes was taken across the bridge seven times on Friday in a relay by groups dressed in official 17th Century freemen's robes.
They hope to raise £40,000 for charities Wellbeing of Women and Orbis.
Freemen of the City of London date back to 1237, when the title was awarded to craftspeople who became the only people in the city with the right to vote.
The freemen met the Lord Mayor of the City of London David Lewis and Lady Mayoress Theresa Lewis before the event began from the north-side of the bridge.
She described the event as "just wonderful", adding: "Hopefully it is a bit for fun for business people to see, whose day may not be full of happiness at the moment."
Joe Phillips, chairman of the Romney Sheep Breeders' Society, said the sheep from a farm in Ashford, Kent, had been trained "to accept the noise" of the rush-hour in the City and cheering crowds.
Last month Amanda Cottrell, from Challock in Kent, drove sheep over the bridge to publicise the restoration of Canterbury Cathedral and a scheme backing local food production.