Director Christopher Guest's satirical targets have included the ultra-competiveness of dog shows (Best In Show), rock pomposity (Spinal Tap) and the bitter rivalry of the folk scene (A Mighty Wind).

Here he sails a little too close to home when he chooses to parody the Hollywood star system and the unedifying sight of actors jockeying for position when the Academy Awards come around again.

Having a pop at the self-absorbed world of luvvies is a bit like shooting fish in a barrel - they're so open to barbed derision that you don't have to try very hard to make them look even more ridiculous than they already are.

Guest asks us to believe that an appalling Jewish TV movie - Home For Purim - about the family of dying matriarch Marilyn Hack (O'Hara) gathering for her favourite holiday - begins to generate Oscars buzz off the back of an internet rumour.

Once you've bought the premise that a film that isn't even finished is garnering Academy speculation, then there is fun to be had as studio executives step in to "broaden its appeal" and warp the movie from its simple origins.

However, there's something missing: the satire is never as cutting as it should be because people who work in Hollywood - from hotshot studio bosses to has-been actors - are beyond parody. How can you lampoon the weird world of Tom Cruise?

What does make this funny is the terrific ensemble playing of Guest's regular cast, from Fred Willard's appallingly crass anchorman to Jennifer Coolidge's clueless producer, a woman whose family fortune came from a nappy-washing business.

O'Hara is terrific as the frumpy veteran who discovers the world of collagen when Oscar whispers in her ear while Shearer's exchanges with his duplicitous agent (co-writer Levy) muster a satirical bite.

There are also some good lines - horrified screenwriter Lane Iverson (McKean) complains about studio tampering with the warning: "if you throw the baby out with the bathwater…you'll get a wet, critically injured baby."

But it's not enough. Even Gervais - who sublimely parodied the vanity and vacuousness of showbiz with Extras - takes a step back as a studio boss who will sell his soul for a sniff of a golden statuette.

It's certainly watchable...but after a couple of decades of nailing his targets, this Guest may have out-stayed his welcome.

Tim Evans