Denise Derbyshire from Wigan and her daughter met the King and Prince William as they waited to see the Queen's Lying in State with other mourners.
King Charles III and Prince William have carried out a surprise walkabout at the queue to see the Queen's Lying in State.
Having just left the Metropolitan Police's Service Special Operations Room in Lambeth to thank emergency service staff for their efforts, the King stopped off nearby to see the 10-mile queue.
Denise Derbyshire said: "It's been worth every minute.
"Couldn't have asked for anything better to meet the King and Prince of Wales on the same day, was absolutely amazing."
Denise added, she told King Charles: "She was very sorry for the loss of his mother."
Some of those queuing called out "Three cheers for his majesty" as King Charles III made his way along the barriers with his son Prince William.
Reaching out their hands to hundreds of the public, many took the opportunity to greet the Royals and photograph them.
In line for the Queen’s lying in state, one lady offered Charles condolences as he shook her hand, and another shouted: “I can’t believe this.”
Dozens shouted “hip hip hooray” as Charles and William moved down the line, stopping for a few moments with each person.
Several people called their friends and relatives on the phone to tell them what they had just witnessed.
The Prince of Wales thanked people for waiting in line for many hours for the Queen’s lying in state, as he shook hands with mourners.
Several people cried after meeting him, and one woman told him: “You’ll be a brilliant king one day”.
Charles left before William, both of them in cars surrounded by police vehicles.