Adele is preparing to headline Glastonbury Festival for the first time ever today, taking to the Pyramid Stage just after 10pm. For fans who aren't lucky enough to be there live, the performance will be broadcast on BBC Two, who will be warning viewers that some bad language is to be expected.

AdeleAdele will headline Glastonbury tonight.

According to the Mirror, the BBC will broadcast a warning ahead of Adele’s headlining set, telling viewers to expect “strong language”. Fans of Adele know that the singer is no stranger to using four letter worlds during her often emotional sets.

“In between performing emotional ballads, Adele is completely herself on stage and tells some hilarious anecdotes. It’s all part of her charm,” a source told The Mirror. “Swearing is in her vernacular, so it’s only natural she’ll be effing and blinding away.”

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“But even though her set will air in a broadcast that doesn’t begin until after 9pm – which is post-watershed – it’s probably for the best that viewers are warned to expect a few naughty words.”

A BBC spokesperson commented: "As with previous years, all live post-watershed performances from this weekend’s ­Glastonbury will be prefaced with a warning for possible strong language.”

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Adele had previously said she would never play Glastonbury, because of her fear of huge festival crowds. Speaking to Q magazine in 2011, Adele said: ''I will not do festivals. The thought of an audience that big frightens the life out of me.”

“I don't think the music would work either. It's all too slow. I'd hate to book a festival and have a f****** anxiety attack and then not go on stage, do you know what I mean?’' But the singer is set to have plenty of support as she takes the stage tonight, as boyfriend Simon Konecki and mother Penny Adkins have both been spotted on site.