The funny thing about A Funny Thing Happened On The Way to the Forum, which opened on Saturday at Melbourne’s Her Majesty’s Theatre, is this: it’s not just funny — it is entirely and unreservedly hilarious.

Forum first opened on Broadway in 1962, though from this staging you’d never know it. There’s not a single joke that doesn’t land, and the 50-year-old-script by Burt Shevelove and Larry Gelbart (better known as the creator of M*A*S*H) is a masterclass in farce. Forum was the first musical for which Stephen Sondheim — doyen and demigod of musical theatre — wrote both music and lyrics. Sondheim’s lyrical dexterity and wily wordplay is in regular form here, but the songs are almost inconsequential, with nary a hummable tune among them — with the sublimely ridiculous Everybody Ought to Have a Maid perhaps the one exception.

Under the sharp, solid direction of the impossibly prolific Simon Phillips, this cast have somehow bottled both lightning and joy, and they dole them out in equal measure from curtain to curtain. Geoffrey Rush as Pseudolus — a role previously tackled by Jason Alexander, Nathan Lane and Whoopi Goldberg — is perhaps as close to theatrical wizardry as anyone will ever get, and reason enough to get your hands on a ticket. All gangly limbs and pratfalls, Rush’s comic timing is a thing to behold, and he’d easily steal the show if it weren’t for the talented cast assembled alongside him.

Adam Murphy as Miles Gloriosus and Gerry Connolly as Marcus Lycus are deft, dexterous and hilarious. Christie Whelan-Browne is pitch perfect and honey-voiced as virgin courtesan Philia, and Bob Hornery’s turn as doddery neighbour Erronius is as clever and heartbreaking as it is side-splitting. The supremely talented Mitchel Butel — as neurotic head slave Hysterium — plays the same hand he did earlier this year in The Producers, but he does it so masterfully that it really doesn’t matter. I’m Calm, Hysterium’s big number, is a highlight.

Magda Szubanski as Domina is marvellous, and she stops the show no less than four times, sometimes with no more than a single word. Somehow, with every sentence that rolls off her tongue, she conjures the ghosts of Pixie-Anne Wheatley, Sharon Strzelecki and Lynne Postlethwaite all at once, yet never trades on them. All of Szubanski’s characters are nuanced, perfectly-timed and utterly unique, and Domina is no exception. Shane Bourne as Senex, Domina’s husband, is perhaps the weakest link in the cast, but he’s still perfectly adequate, and managed to ad-lib his way out of a costume-snagged-on-co-star mishap with élan.

The evening’s biggest surprise is Hugh Sheridan, star of Packed to the Rafters, as Hero. Sheridan’s golden voice and adroit charm transcend the dull, pointless mugging we’ve all seen him lumbered with on the Channel Seven drama.

The glorious theme-park-cum-forum set and clever, campy costumes by Gabriela Tylesova are fantastic, and Andrew Hallsworth’s choreography is a perfect fusion of silly and slick.

Forum is delightfully camp, perfectly executed raucous fun. Go see it.

The details: A Funny Thing Happened on the Way to the Forum plays Her Majesty’s Theatre until December 16. Tickets via Ticketek.