The Tony award-winning musical adaptation of low-budget Irish film Once has opened in the West End to a rousing reception.
Sir Terry Wogan, Graham Norton and comedian Dara O'Briain were in the audience at the Phoenix Theatre.
O'Briain was one of the first to hail the show on Twitter calling it "An utter joy... hugely recommended."
Director John Tiffany said: "This was coming home for all of us in the creative team so it was a big deal."
Unusually for a West End show there was no orchestra, with the entire score provided by the on-stage cast who all talented multi-instrumentalists.
The cast were called back for four enthusiastic encores on Tuesday evening, following the love story between a lonely vacuum cleaner repair man and part-time busker in Dublin, and the young Czech single mother who sees the spark in his music.
The Evening Standard praised the show's "delicate soulfulness and truthful charm".
In his four-star review, The Guardian's Michael Billington said it "wins you over with its simplicity, charm and air of sweet melancholy."
But he added: "Admittedly there are times when the Czech heroine irritates slightly with her folk-wisdom and secret sadness."
The musical is based on the 2006 film, written and directed by John Carney and starring Irish musician Glen Hansard as the unnamed "Guy" and Marketa Irglova as the "Girl".
The main track from the film Falling Slowly won the 2007 Oscar for best original song.
Adapted for the stage by Enda Walsh, the show opened off Broadway in December 2011, before transferring to Broadway in February 2012.
In May it was nominated for 11 Tony awards, winning eight - including best musical, and best actor for star Steve Kazee.
But Tiffany - who won best direction of a musical - told the BBC news website the London move was always going to be special for personal reasons.
"It was amazing, my dad and mum were in the audience and the show is a love letter to them in a lot of ways, they taught me how to love music."
Casting two fairly unknown actors - Declan Bennett and Croatian Zrinka Cvitesic in the lead roles - was "fundamental" to the story, added Tiffany - a former associate director at the National Theatre of Scotland.
"You can't know anything about them or have any expectations," he said. "Although [Cvitesic] is the Kylie Minogue of Croatia, but we don't know that here obviously."
In his review, The Telegraph's Charles Spencer called Once "lip-quiveringly sensitive, almost ostentatiously sincere and hugely successful".
But he added: "There are some corny moments... and the dialogue is often cheesy."
Bennett - an English singer-songwriter currently based in New York - said his first experience of Once was watching the film at Glastonbury "when it rained all weekend".
"It was on in one of the tents at like three in the morning and I dragged one of my mates down and we sat with about 20 people and it knocked me for six," he said. "The music was gorgeous."
Cvitesic posed for pictures with the Croatian ambassador at the after-show party. "He went to the first preview and said, 'I'm coming back for the press night'," she said.
However the star revealed she had still to see the film on which the musical is based.
"I wasn't allowed," she explained. "My director told me not to see the movie or the play on Broadway. There was one sentence he gave us at the first rehearsal, he said, 'You're not repeating anything, you are creating your own.'"
Once arrives in the West End during a particularly healthy period with both revenues and audiences high but Tiffany insisted the success in New York wouldn't guarantee a return in the UK.
"You've got to make the show right for where it is, so we didn't come resting on any laurels at all. We knew it had worked in New York and that was a big surprise.
"I hope we find our audience because no-one knows who we are at the moment, but people coming in are having the best time ever so I hope that continues."
Once is at the Phoenix Theatre until 30 November.