SHEFFIELD, England (AP) _ The difference between ``The Full Monty'' and ``The Full Monarchy'' is elemental: Prince Charles keeps his clothes on.

But the heir to the throne was a hit nonetheless Friday at a 50th birthday party staged in his honor featuring a cast member from the hit film about unemployed Sheffield men who turn to stripping.

The icing on a birthday cake in the shape of a security guard's cap proclaimed ``The Full Monarchy.'' Cast members all wore such hats in the movie's finale.

Charles visited a set used in the 1997 movie about the Yorkshire industrial city to promote the work of his charity, the Prince's Trust.

Taking a lead from Hugo Speer, who played one of the main characters, ``Lunchbox,'' in the film, Charles quickly mastered the steps and joined in recreating a scene where the men start practicing their dance routine while waiting in line at a job center.

``I've even been given a bit of choreography on how to do things in a queue,'' Charles said.

``He's a cinch _ a natural,'' Speer said of the prince. ``He asked for a few tips but didn't need them. It looks like he's been practicing in his bedroom.''

After his performance to the song ``Hot Stuff'' by Donna Summer, the prince was serenaded by hundreds of youngsters who sang ``Happy Birthday to You.''

During an earlier visit to a drug rehabilitation center in Sheffield, Charles encountered a warm admirer in 78-year-old Elaine Glaza.

``Can I kiss you?'' she asked.

``Absolutely,'' said Charles, and some bystanders shouted ``Go on, Charlie!'' Mrs. Glaza also gave him cuff links and a carnation after she kissed his lips.

Charles, who reaches the half-century mark Saturday, began his birthday celebrations Thursday night with a private party at Hampton Court Palace. On Friday night, Queen Elizabeth II planned a party at Buckingham Palace.

Camilla Parker Bowles, Charles' longtime love, was among the guests Thursday, but the event produced no pictures of the two of them together. She is hosting a party for Charles on Saturday at Highgrove, his country home.