Sarah Crompton: No one could have predicted James Corden's success

At the party Nicholas Hytner threw to mark his departure from 12 successful years as artistic director of the National Theatre, he made a speech. "It's very good of you all to come here today," he said to the assembled crowd "to celebrate…" And then there was an artful pause: "The man who launched the career of James Corden."

It's a good gag, but it is at least possible that when the history of 21st century entertainment is written, it won't seem a joke so much as a prescient tribute to one of the era's most surprising stars. As Corden gets ready to follow in the footsteps of Broadway royalty such as Hugh Jackman and Neil Patrick Harris and host the Tony awards on Sunday, he is taking his place in the American theatrical pantheon.

Of course, as CNN felt obliged to point out to its viewers, he has been on stage before. Although familiar to American audiences as host of The Late, Late Show on CBS, we Brits know him both for his performance in Alan Bennett's The History Boys, as the ebullient Timms, and his show-stopping turn as the harassed servant in One Man, Two Guvnors, Richard Bean's updating of Goldoni, which gave Hytner one of the triumphs of his time in charge. That performance brought Corden his own Tony award for best actor in a play, which he won in the face of opposition so strong it included Philip Seymour Hoffman.

That award and the gracious acceptance speech Corden produced marked a turning point in a career that has had enormous highs – The History Boys, Gavin & Stacey which he co-wrote and in which he starred — and then a number of cringe-making lows, including his embarrassing presentation of the Brit awards and the movie Lesbian Vampire Killers.

No one at his low points could possibly have predicted that this chubby Brit would become one of the most successful of US TV presenters. Those flashes of comedic brilliance that he has always shown – for example in the Comic Relief sketch where he dressed down the English football team including David Beckham – seemed too self-deprecatingly British to transfer across the pond.

Yet he has parlayed that down to earth charm into a winning hand, principally by virtue of one stroke of absolute genius – the invention of Carpool Karaoke in which he invites stars such as Adele, Jennifer Lopez, George Clooney and Julia Roberts to share a car with him on his way to work and to sing along to the songs he plays on the stereo.

In the stale world of the chat show sofa where everybody wearily plays the game of selling their latest movie, it feels like a blast of invigorating fresh air. Just as parenting guides recommend the car as a place to talk deeply to your children, so the format of singing along in unison with the amiable Corden seems to liberate the stars to show the charisma that made them famous in the first place. It isn't exactly revelatory, but it is both weirdly life-enhancing and extraordinarily successful, with the Adele segment attracting 107 million views online.

In this week's segment, to publicise the 70th Tonys, Corden hits the New York streets and gives Hamilton's creator Lin-Manuel Miranda and Broadway legends Audra Mcdonald, Jesse Tyler Ferguson, and Jane Krakowski a ride and incites them to join in a rousing show tunes singalong. Both the latter divide their time between the stage and TV. "Tell me which do you prefer, theatre…" Corden asks with the sweetest of smiles…"Or money?"

I'd like to see Corden himself chose theatre one day soon – but the success of his US television career will probably mean that presenting the Tony awards is the nearest he comes to the boards for some time to come.

Watch the Carpool Karaoke here: