Neil Patrick Harris

The worn-out rag that is reality TV has tarnished the novelty of seeing celebrities reveal, if not talents exactly, then capabilities in unexpected fields. It is now almost impossible to turn on the TV in any English-speaking country in the world and not be faced with a forgotten actress of the 80s learning how to flamenco or flambé.

But when it was announced earlier this year that two great American institutions would come together, with the hugely popular American satirist Stephen Colbert appearing in a one-off gala performance by the New York Philharmonic of Stephen Sondheim’s Company, tickets for the four perfomances sold out almost immediately.

And judging from last night’s opening performance – in which Colbert appeared alongside other relatively inexperienced musical stars, including Martha Plimpton, Jon Cryer, Christina Hendricks and Neil Patrick Harris, as well as more practised ones such as the wonderful Patti LuPone – the "famous person does something new" format produces results a lot more sustaining than those usually found at the end of Celebrity MasterChef.

Sondheim’s musical about the simultaneous fear of and desire for commitment in a young man (played here by Patrick Harris) had surprising power: it reportedly wasn’t until last night that the director, Lonny Price, was able to get all his cast together at the same time. Colbert didn’t even take a break from his nightly TV show, The Colbert Report, this week – and one hour after the curtain came down, fans could even see him back in his usual persona on TV. Instead, most rehearsing was done via stand-ins and Skype. Yet, saving the occasional drop of a cane, there was little sign of awkwardness or mutual unfamiliarity. Instead, everyone simply looked like they were having the time of their lives.

Admittedly, many of those on stage needed only the minimum of assistance to act their parts because they were playing similar characters to existing TV roles: Jon Cryer’s bored, put-upon husband was a variation on the bored, put-upon ex-husband he plays on Two and a Half Men; Neil Patrick Harris’s eternal bachelor was not a million miles away from his turn in How I Met Your Mother; and Christina Hendricks plays a luscious, alluring air hostess similar to – well, you get the point. (In some ways these, shall we say, personae were even more firmly established in the flesh: when Hendricks casually slipped off her clothes and stood in the middle of the stage in a silk slip, she proved that her famous Mad Men hourglass requires no padding.)

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The TV actors were outshone vocally by those more experienced on stage, but they stood up pretty well, bringing out Sondheim’s occasionally overlooked comedy, with Hendricks and Colbert in particular nailing their lines. Patrick Harris, who has appeared in musicals in the past including Sondheim’s Sweeney Todd, didn’t quite hit some of the high notes, but he gained in confidence as the performance progressed.

The real surprise was Colbert, playing the resentfully (if only sporadically) teetotal Harry. Although he’s sung on TV before – most recently on Late Night with Jimmy Fallon last week when he performed the viral internet hit Friday – nothing suggested his ability to convey the heartbreaking emotion he showed here in one of Sondheim’s most beautiful and underrated songs, Sorry-Grateful, about the simultaneously soul-crushing and faith-restoring nature of marriage. "You always are what you always were,/ Which has nothing to do with, all to do with her," sang Colbert, eyes and voice brimming with unaccustomed authenticity.

The chic and clever minimalist set – featuring only sofas serving as apartments, bars and bachelor-pad bedrooms – echoed perfectly the spiky elegance of Sondheim’s music. But the real triumph of this performance was its sense of joy. And that’s not something you can say about Celebrity Big Brother.