Glastonbury 2015 line-up: The Libertines hot bet to fill Florence + The Machine's slot

Emily Eavis is yet to announce who will be rocking the festival tonight

The Libertines are not currently on the Glastonbury line-up but may be making an appearance on Friday evening (Getty Images)

Glastonbury's Pyramid Stage will be silent for almost four hours tonight if the official website line-up is anything to go by, but rumours are circulating that The Libertines have been booked on the sly.

Update: The Libertines confirmed to play Glastonbury 2015

Florence + The Machine have been bumped up to the headline slot in place of the Foo Fighters (Dave Grohl broke his leg falling off stage - big drama) leaving a chasm of nothingness between Motorhead finishing at 6.30pm and their start time of 10.15pm.

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Organiser Emily Eavis has confirmed that a band will be performing during that time but in the name of anticipation and surprise, is refusing to give anything away.

"There is definitely something filling that gap but under no circumstances will it be announced," she said. "Luckily it's been a proper secret, a proper surprise, which actually is quite hard to do now because things get out."

Eavis revealed that "only about four people other than the band" are in on the secret, with festival staff also in the dark.

The one thing we know for sure is that the act has never played the Pyramid Stage before. The Libertines were booked for the main stage in 2004 but had to pull out and were replaced by Supergrass. They played the Other Stage to wide acclaim in 2003.

Pete Doherty and Carl Barat's group have a gig booked in Russia on Saturday but are expected to share something exciting with fans on their brand spanking new Instagram account at some point today.

The name "Albion" has also appeared on a piece of techie's duct tape under Florence Welch (above) which strongly hints it will be the Libertines - or at least Doherty - as Albion is a frequent theme in his music and poetry as well as the title of a Babyshambles song.

Bastille and Frank Turner have confirmed that they will be popping up unannounced at Worthy Farm, while Blur are heavy favourites to perform a secret set.