Cornwall's lord lieutenant will form part of a group standing guard around the Queen's coffin in Westminster Abbey during her state funeral.
Lord Lieutenant Edward Bolitho is also a member of the Honourable Corps of Gentlemen at Arms, which acts as bodyguard to the monarch.
Paying tribute, Mr Bolitho said the Queen would be remembered for "duty, unity, and continuity, but also fun".
He said the Queen had been able to leave people with a smile.
Mr Bolitho said: "How do you try to sum up what someone's done in a 96-year-old life of which, certainly, 80 of them were spent on duty, and duty is the thing we will remember the Queen for, duty, unity, and continuity, but also fun actually.
"Whenever anyone met her, they always went away feeling a little bit better, with a smile on their face and that was a fantastic art for someone to have."
Due to his role as a member of the Honourable Corps of Gentlemen at Arms, the lord lieutenant will also play a central role in the Queen's funeral arrangements, taking part in the procession from Westminster Hall to Westminster Abbey on the day of the Queen's funeral, and standing guard around the coffin during the service.
Mr Bolitho said: "We'll be around the coffin in Westminster Abbey, and then processing with the coffin from Westminster Abbey down to Wellington Arch, and then going to the committal service, which will be held in St George's Chapel in Windsor."
Mr Bolitho said he thought King Charles would be a "superb sovereign".
He also said Cornwall was privileged to have Prince William and his wife Kate as the Duke and Duchess of Cornwall.
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