Zac Efron at the Me and Orson Welles UK premiere

Let's get this party started right now! We have the red carpet, we've got the teenage hordes and we have Mr Zac Efron (TM). So that must make this the London premiere of High School Musical 4 – rockingest, sockingest High School Musical of them all. Right? Photograph: Ian West/PA

Wrong. This, in fact, is the UK premiere of Me and Orson Welles, the new film from Richard Linklater. The good news: Me and Orson Welles is a backstage caper in which Zac Efron helps to put on a show. The bad news: the show in question is a Shakespeare tragedy. None of the characters play basketball. None of them do much dancing. And Efron is paired, not with grinning Vanessa Hudgens, but with a pensive-looking Claire Danes Photograph: Dave M Benett/Getty Images

Whoah, where's Zac? That's not Zac! This guy looks nearly old enough to be Zac's father and his name is Christian McKay. Turns out that McKay plays the 'Orson Welles' dude. Welles, we are guessing, is some kind of curmudgeonly teacher who hates basketball and winds up getting pushed in a swimming pool, where he shakes his fist in fury. But like we say, we're guessing Photograph: Richard Young/Rex Features

And that's not Zac either. This guy's name is Ben Chaplin. He takes the role of 'George Coulouris'. Check out the glasses: he must be some kind of nerd. Georgie Coulouris: the maths professor who keeps mislaying his briefcase. Something like that, surely Photograph: Mike Marsland/WireImage.com

Not Zac! Kelly Reilly, we are told, plays 'Muriel Brassler' in this here Orson Welles movie. Sexy mom? Likes a tipple? Always throwing house parties and trying to lure Zac into her boudoir, to hilarious comic effect? Photograph: Mike Marsland/WireImage.com

And no, that's not Zac either. It is, in fact, Hugh Dancy – another actor, but not one who's in this particular movie. Turns out Dancy is married to Danes, who is in the movie where she's pretending to go out with Zac. Somehow or other it all comes back to Zac Photograph: Dave M Benett/Getty Images

And oh, thank heavens, there he is. Bright of eye and fresh of face; cosying up to co-star Megan Maczko and making her dreams come true. Efron here to plug his role as 'Me' in Me and Orson Welles, which is not to be confused with High School Musical and features no basketball whatsoever. We hope that has now been cleared up Photograph: Dave M Benett/Getty Images