Running time: 113 mins. Starring: Zac Efron, Christian McKay, Claire Danes, Ben Chaplin, Kelly Reilly, Eddie Marsan, James Tupper. Director: Richard Linklater.

HIGH School Musical star Zac Efron attempts to step away from cutesy, teen-friendly fare with this handsome period piece.

To a large degree he succeeds, testing his acting mettle as part of an impressive ensemble cast in a drama inspired by Orson Welles’s notorious 1937 Broadway staging of Julius Caesar.

However, you evidently can’t take the boy away from the musical completely, because Richard Linklater’s film culminates in the handsome pin-up singing sweetly to a hushed theatre audience, while plucking a ukulele that doubles as a lute.

For all of the attention focused on Efron, Me & Orson Welles is ultimately a showcase for newcomer Christian McKay as the bullying, egocentric titular legend.

With a rumbustious, eye-catching portrayal that puts his co-stars in the shade, the Bury-born actor can look forward to an Oscar nomination as supporting actor for his revelatory performance.

Every moment McKay is on-screen, we’re fascinated to see which member of the company Orson will manipulate next to achieve his grand vision.

Based on the novel by Robert Kaplow, Linklater’s film unfolds through the eyes of fresh-faced high-school student Richard Samuels (Efron), who happens to be in the right place at the right time and blags the role of Lucius, replacing a kid who had a personality problem with Orson.

”Meaning?” asks Richard. “He had a personality,” replies a member of the troupe, warning the new boy not to upstage the production’s conceited director and star.

The great man is cast as Brutus, and he dispatches Richard to learn his lines with beautiful production assistant Sonja (Danes).

Meanwhile, the selfish star drives the rest of the company to the brink of mutiny, not least fellow thesp and co-star George Coulouris (Chaplin) and Mercury Theatre president John Houseman (Marsan). While the production threatens to collapse around him, Richard pursues the seemingly unattainable Sonja.

”Fight for her, that’s what she wants,” fellow actor Joseph Cotten (Tupper) advises. “I’m not sure that’s who I am,” counters Richard.

Me & Orson Welles is a gently-paced nostalgia piece that recalls Mrs Henderson Presents, set to a score re-arranged and performed by Jools Holland and Eddi Reader.

Efron’s role doesn’t stretch him, he plays another likeable guy chasing the girl, but at least this film doesn’t contrive a happy ending when reality would dictate otherwise.

Chaplin is gentle comic relief as a pessimistic, plummy Brit, and Kelly Reilly adds a touch of glamour as insecure diva Muriel Brassler, who knows how she wants to be lit to look her best.

Partly shot on location on the Isle of Man, with the restored Gaiety Theatre standing in for the Mercury, Linklater’s picture evokes a vibrant period in New York history.

Not once do we doubt the illusion.