Australia's Herald Sun visited the set of Harry Potter and the Half-Blood Prince last year and interviewed Daniel Radcliffe. The article describes Leavesden Studios and a day on the set when Slughorn's Christmas party was being filmed. Radcliffe’s not in this scene, but he’s happily watching what Jim Broadbent, who makes his Potter debut in the Half-Blood Prince as Horace Slughorn, does with his several go-throughs. Slughorn is greeting guests, including Luna Lovegood (played by the wonderfully eccentric Evanna Lynch) dressed up like a silver Christmas tree, and with each take Broadbent mixes it up — easy stuff for a veteran of his status. ‘‘I wasn’t in the first shot this morning but I went down to watch it just ’cos . . . I’m just interested in it and I want to see how other people act together. It’s about learning, for me,’’ Radcliffe says.