The Prince of Wales has taken his first ride in a black cab before meeting more than 100 drivers.
Prince Charles paid his own fare of £15.20 at the end of the journey
Taxi driver John Sheen took Prince Charles in his licensed Hackney Carriage to Hanover Square where he joined cabbies for a mug of tea.
He then drove the prince to a reception at Clarence House to thank taxi drivers for their contribution to the city.
Afterwards Mr Sheen said: "You know what I'm going to say. Guess who I had in the back of my cab today?"
He added: "I don't think they'll believe me. He's never been in the back of a cab before.
'Very good tip'
"He said as a boy he went on a double-decker bus but that's about it as far as public transport goes."
Mr Sheen, who has been a London cabbie for 30 years, picked up his royal customer at Kensington Palace in his black TX2 taxi.
He said the prince paid his own fare at the end of the journey.
"The round trip was £15.20 and in total he gave me £20 cash all out of his own pocket."
Asked if this was a good tip, Mr Sheen replied: "That's a very good tip, I would like that every day."
A spokeswoman for the prince said he was keen to ensure the drivers received recognition for providing such a safe, reliable service, and for their charity work.