An OK copy of the original

Back in the 1970s, the British comedy troupe Monty Python would often dryly announce, “and now for something completely different.”

Well, not much is different about the revival of “Monty Python’s Spamalot,” the musical that’s based on their 1975 film “Monty Python and the Holy Grail,” that opened Thursday night at the St. James Theatre. Save for new sets and actors, it’s more or less the same as it was when it premiered 18 years ago, only not as special or exciting.

Which begs the question — a bit like wondering how on earth a tropical coconut wound up in tenth-century England — what is ye olde “Spamalot” doing back on Broadway right now anyway? 

Looking on the bright side of life, audiences can always use a laugh, especially these days, and director Josh Rhodes’ fun-enough staging has a decent number of giggles thanks to ironclad source material. 

But the core gag of putting scrappy Python on a glittering stage, while sending up musical theater tropes like “Urinetown” and “[title of show]” also did around the same time, does’t land nearly as freshly or successfully as it did when Eric Idle and John Du Prez’s show debuted in 2005. 

Never hilarious, the revival stalls out at pleasant. Spamalot, laugh a little.

Nonetheless, King Arthur, played by James Monroe Iglehart, once again trots across the not-yet-united-kingdom to recruit his Knights of the Round Table and then lead them on a God-sanctioned quest to find the mythical Holy Grail. 

That intrepid crew includes the perpetually terrified Sir Robin (Michael Urie), the conspicuously macho Sir Lancelot (Taran Killam), Sir Bedevere (Jimmy Smagula) and Sir Galahad (Nik Walker), who still can’t settle on what his favorite color is 48 years later. 

The King is helped along by his neglected sidekick Patsy (Christopher Fitzgerald), a veritable Mr. Cellophane, and the aquatic chanteuse the Lady of the Lake (Leslie Rodriguez Kritzer).  

They’re all enjoyably zany as they become a series of oversize characters, from mud-covered mothers to amputee swordsmen the fearsome Knights Who Say Ni. 

The always great Urie, as Sir Robin, has the daunting task of selling the show-stopping number “You Won’t Succeed On Broadway,” which goes, “You won’t succeed on Broadway if you don’t have any Jews.” The song is risky right now, yes, but it’s intended to be celebratory, affectionate and fun — and audiences are responding to what has always been the funniest song in the show in exactly that spirit. 

Kritzer brings vocal fireworks and attitude to the Lady of the Lake, but I wish she didn’t chew the scenery so much so soon. The should-be explosive song “Diva’s Lament,” in which she complains “now we’re halfway through Act 2, and I’ve had nothing yet to do!,” is less effective for it. 

The best addition to this “Spamalot,” though, is “SpongeBob the Musical” actor Ethan Slater as the frustrated historian, wimpy Prince Herbert, the killer bunny and a spate of other weirdos. The Python style of comedy is much bigger than punchlines. It’s all at once bizarre, class-clowny, ridiculous and bold — qualities that come naturally to an actor who once played a talking sponge. He’s a riot.

The cast yuks it up on Paul Tate dePoo III’s lackluster set that relies on oddly dreary projections to change up locations.

“Monty Python and the Holy Grail,” of course, was not a big-budget project and “Spamalot” needn’t be either. But if you can’t afford to be spectacular, like Mike Nichols’ original production was, then make the design clever and funny. Nope. This one settles for mere functionality. 

It’s yet another missed opportunity for the revival to be something at least a little different.