The King and Queen Consort received a warm welcome as they visited Doncaster to mark the conferral of city status.
Charles wished the city “every possible success for the next 2,000 years” as he gave a short speech at Mansion House.
Crowds, including Paul Elliott of the Chuckle Brothers, lined the streets to greet the royals.
Charles spent six minutes greeting well-wishers during an unplanned walkabout outside.
Tammy Houghton, 50, who shook hands with the King, said: “He said he hoped we’d not been stood here too long.
“We’ve been here two and a half hours but I didn’t tell him that!”
In his speech, Charles said: “The warmth of the welcome we have received today is all that we have come to expect in a county which is renowned for its sense of belonging and its feeling of community.
“It is something which all who know this wonderful part of the world will recognise instantly and can never forget.
“Here in Doncaster, you have, of course, a great deal of which to be proud: from your Roman origins 2,000 years ago to your crucial role in the Industrial Revolution and in the creation of this nation’s railway network, to the pre-eminent place you occupy in the horse-racing world.
“For all those reasons, and many, many more, it is entirely fitting that Doncaster should be chosen as one of the new cities created to celebrate the late Queen’s Platinum Jubilee.
“We mark that occasion now in memory of my beloved mother’s lifelong dedication to all that is best about our country. She would, I know, be immensely glad that this honour should be conferred on a place where it is so richly deserved.”
Junior civic mayor Eva Shaw-Lewis, nine, said: “When I was lucky enough to be chosen as Doncaster’s junior civic mayor only a few weeks ago I knew that I would get to meet a lot of new people and attend lots of exciting events, but I never dreamed that I would be lucky enough to meet the King and Queen Consort.”
Charles and Camilla also met volunteers at a reception after the ceremony to mark the city status.
Michael Trotter, 65, from the Vulcan to the Sky Trust, which wants to return the aircraft to the skies, spoke to the King.
The trust has kept the last airworthy Vulcan at Doncaster Sheffield Airport but is looking for a new home for it.
Mr Trotter said: “He used to fly a Vulcan and remembered how small the cockpit was.
“He was interested in the work we do.”
The King also spoke to Paul Iwanyckyj from the Association of Ukrainians in Great Britain.
Mr Iwanyckyj said: “He expressed an interest in how many refugees are here. We have about 200 here, mainly women and children.
“He wanted to know how we look after them.”
Charles used his own pen to sign the visitors’ book before being presented with a Paddington Bear and local honey.