Taylor Swift has come to the rescue of a Sydney theatre company whose production hit a last-minute snag when they were refused permission to use the singer’s hit Shake It Off.

The Belvoir Street Theatre play Seventeen, due to open this week, features a cast of actors in their 70s playing 17-year-olds on their last day of school.

“There’s this great moment where they ‘Shake It Off’, and they know all the words and have amazing moves,” Belvoir director Anne-Louise Sarks said on Twitter.

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“But we’ve just at the last minute been told we can’t have the rights to the song.”

Ms Sarks began a furious social media campaign on Tuesday, asking the US star to step in to rectify the situation.

Some of the cast celebrating the news. Photo: Twitter

The theatre troupe tweeted to actor Russell Crowe and comedian Tim Minchin — as well as accounts linked to Swift’s “army” — to get the star’s attention.

The hashtag #greygrey4taytay soon began trending in Australia, and finally, late on Tuesday, success came — fittingly, in the form a single tweet.

“Permission granted, @BelvoirSt,” Swift wrote. “Good luck with your opening night.”

Ms Sarks said she was “overwhelmed” that Swift had come through for the company.

“It’s thrilling, it’s so exciting, and most of all it’s a huge relief for the show,” she said.

She wrote to Swift on Twitter: “Your support for artists is a thing to behold.”

Swift, who has 60 million Twitter followers, is not afraid to wield her power through social media.

Earlier this year, she wrote on her Tumblr of her intention to withhold her album 1989 from streaming service Apple Music when it initially decided not to pay artists during a free trial.

Within days, the tech giant did an about-face.

Permission granted, @BelvoirSt. Good luck with your opening night 🙂

— Taylor Swift (@taylorswift13) August 4, 2015

A huge and heartfelt thank you to everyone who tweeted #greygrey4taytay. Thank you @taylorswift13, we are officially joining the fan club!

— Belvoir (@BelvoirSt) August 4, 2015