Movies
Staunton starred as Dolores Umbridge in 2007's Harry Potter And The Order Of The Phoenix, while Broadbent plays the part of Horace Slughorn in this year's movie.
Broadbent told The Daily Telegraph: "I did say to Imelda Staunton, who had just done one, that I had been offered this and she said it was lovely and go on and do it.
"She said they treat you very well and it is a very easy, comfortable atmosphere. I also knew [director] David Yates, who is a delight to work with. So it was not a decision that took much making."
He added that his character is introduced in the movie in the guise of a chair as he hides from the Death Eaters.
Harry Potter And The Half-Blood Prince is released in UK cinemas on July 15.
Movie Reviews
'Extremely Loud & Incredibly Close' reviewTom Hanks features in a long and winding journey through New York after 9/11
At the Movies
David Lynch: 10 reasons to worship himIt's time to celebrate director David Lynch as the BFI screens a season of his films.
Movies Interviews
Max von Sydow 'Extremely Loud' interviewActing legend Max von Sydow on Extremely Loud & Incredibly Close, The Exorcist and Flash Gordon.
Box Office Charts
'The Woman in Black' wins UK box officeThe Woman in Black beats The Muppets and Star Wars at the the UK box office.
