"Well, yes, you know, I was waiting," Broadbent said with a burr of mock indignation. Broadbent has plenty of opportunity for vainglorious moments in his role as professor Horace Slughorn, the latest colorful faculty member to join the movie franchise, which (finally) returns this summer with " Harry Potter and the Half-Blood Prince."

"It's wonderful to be part of this now, to come in at this stage, because they've got it running so smoothly now, it's amazing to see," said the 59-year-old Broadbent, whose screen career dates to 1978. "In the first one, I'm sure there was a bit of nervousness about whether it would all work, but now it's a unique position to be in, to be making a blockbuster without a lot of nervousness. It's hugely beneficial for the creativity to have a great deal of certainty about the process and the success."

Broadbent, who calls Slughorn "a good man, a decent man, but a weak man," arrived at the "Potter" set fresh from filming " Indiana Jones and the Kingdom of the Crystal Skull." If the success of the "Harry Potter" movies seems like clockwork, he said, it's because of gears set in place with the first film, back in 2001. There was the casting of the three main stars -- Daniel Radcliffe, Emma Watson and Rupert Grint -- who Broadbent said are "so contained and brilliant and professional," and the reverence for the source material, the books of J.K. Rowling.

"I saw the first film when it came out, and it was so brilliantly conceived," Broadbent said. "You read the book and then you see the film and every moment you think, 'That is exactly how I imagined it.' It was not absolutely faithful because you cannot be when you take it to film, but the feel and look of it was terribly meticulous. That care led to this great success. The reading audience has been satisfied with it and wanted more and gone along with it."

David Yates, who returns as director for the new "Potter," called Broadbent an "actor's actor" and has worked with him before on a British television movie called "Young Visitors," which also starred Hugh Laurie and Bill Nighy. "He works exceptionally hard, and he makes everything look exceedingly easy," Yates said.

Broadbent's Slughorn gravitates toward celebrity and adores the reflected glow of exceptional people. Slughorn can't get enough of big names or flaunting them, much like the "Potter" franchise and its use of every notable British actor.

"Well," Broadbent said, again puffing himself up with a winking bit of Slughorn. "Not every actor gets invited. I know some who are still waiting."