It is arguably the third most talked-about topic when it comes to the subject of Glastonbury.
After the thorny issue of securing tickets and the all-important weather forecast, the Glastonbury line-up comes under close scrutiny – particularly when it comes to speculation about its headline acts.
October's revelation that Radiohead is to headline the Pyramid stage on Friday night sent music fans into a frenzy – and cranked the rumour mill into overdrive over who else could top the bill.
The cryptic announcement has left fans wondering which will be revealed next – and how.
In December, festival organiser Emily Eavis revealed that "90 per cent of the line-up is confirmed", although she ruled out two other rumoured headliners of the Stone Roses and Daft Punk.
As 2018 is a fallow year for the festival, Eavis added that they are planning a bumper line-up in 2017 to "cram in" two years worth of music.
Here, we present the latest Glastonbury rumours.
Foo Fighters – confirmed
Foo Fighters must be experiencing a case of Déjà vu after announcing that they will be headlining Glastonbury for the second time in as many years.
The US rock band will take to the Pyramid Stage on Saturday night of Glastonbury this year after they had to bow out of 2015's festival when frontman Dave Grohl broke his leg while on tour in Sweden. Florence + The Machine stepped in at the last minute to cover their Friday night performance.
Foo Fighters, who emerged from the dissolution of Nineties grunge band Nirvana and are best known for hits such as All My Life, have been one of the bookies' favourites to top Glastonbury's bill ever since their no-show in 2015.
However, they didn't appear on 2016's bill, as expected, with Muse, Adele and Coldplay headlining across the weekend instead.
The band made the announcement at a "secret" gig last week at the Cheese and Grain in Frome, Somerset.
"Imagine the village hall you had your 7th birthday party, filled with Foos fans who can't believe their luck," said a Telegraph reporter in attendance, ahead of the performance's start. "Everyone keeps wondering up to each other grinning and saying "how weird is this?!'"
Radiohead – confirmed
It's been almost 20 years since their legendary 1997 Pyramid Stage outing, and what better way to mark the anniversary with another iconic performance in 2017? Festival organisers used the BBC's Glastonbury webcam to announce the first headline act of Radiohead – by slowly revealing a replica of the band's logo beside the half-constructed Pyramid stage at the site in Somerset.
The ground composition took two days to complete, but eagle-eyed fans spotted early on the shape taking form bore a remarkable resemblance to the bear symbol used by Radiohead to promote their 2000 album, Kid A. The following day, the festival confirmed its first headline act via its official Twitter feed.
Aside from a surprise appearance in one of the festival's 'special guest' slots on the Park Stage in 2011, Radiohead last played Glastonbury in 2003 with a spine-tingling headline slot on the Friday night.
Fans – somewhat frustrated by the band's infrequent live performances – have waited a long time to see Radiohead return to the Pyramid Stage. And it would seem even the band themselves are just as excited.
In a recent interview broadcast on BBC 6 Music about the band potentially being asked back to play on their 20th anniversary of their 1997 appearance, Radiohead's Ed O'Brien said: "I would love to, I mean I go to Glastonbury every year, it’s my carnival, to be asked to play at Glastonbury again would be magic."
Ed Sheeran – rumoured
The singer has made no secret of his desire to perform at the festival in recent years – and, if recent events are anything to go by, he just might get his wish in 2017.
On December 15, The Sun reported that Sheeran would be headlining the Pyramid Stage on Saturday night, although the story has not yet been confirmed by the singer's representatives or by the festival organisers.
And in an intriguing turn of events back in November, betting was suspended on the singer headlining the festival next year after a flurry of bets.
Bookmaker Ladbrokes said his odds of headlining dropped from 7/1 to 1/3 after bets were placed "at a rate of knots".
However, it is unclear whether this sudden flush is down to a well-placed festival source or his cameo in the new Bridget Jones film, where he is shown playing at Glastonbury.
Sheeran has been on hiatus from his music career but his third album is expected to be released in 2017, specifically January. Fans got terribly excited in December when he ended his social media hiatus a year after it began by posting a blue square to his Twitter and Instagram profiles.
The Stone Roses – rumoured
Rumours about the band playing the festival first surfaced in 2012 and have yet to subside.
The Stone Roses are touring next summer but a gap in their live date schedule in June could accommodate a set at Glastonbury, which is what sparked this new wave of speculation among evangelical fans.
Initially, their were "strong reports" of the band grabbing the Friday headline slot, but since it has now been revealed Radiohead are to occupy this space the rumour mill now believes they will close the festival on Sunday instead.
However, this gossip was scotched by Emily Eavis in an interview last month.
Fleetwood Mac – rumoured
This iconic band is on the wish list of the high priest of Glastonbury himself, but as much as Michael Eavis would like to see them perform at his festival he said he "can't afford" to bring Fleetwood Mac to Worthy Farm.
Still, this hasn't stopped mounting speculation that Stevie Nicks and co will grace one of the main stages with a headline slot in 2017.
Ever since the band's comeback in 2013, fans believe they would be a perfect fit for the 'golden oldie' Sunday afternoon slot on the Pyramid Stage.
However, if organisers do decide to shell out for the band they may prefer to get their money's worth with a more prominent outing in the form of a headline slot.
Daft Punk – rumoured
Like Radiohead, Daft Punk played the festival nearly 20 years ago in 1997 – and apparently this is enough to spark rumours of an "anniversary" headline slot in 2017.
And, like Radiohead, they have also popped up for an unannounced surprise set.
Talk of a 2017 world tour has added fuel to the rumours, but Emily Eavis flat-out denied they were coming back to headline at Worthy Farm, two decades after they conquered the dance tent.
Lady Gaga – rumoured
A tight-lipped response from the Poker Face singer appears to have dropped the biggest hint yet that she will return to Worthy Farm in 2017.
When asked in an interview whether she would be performing at Glastonbury, Lady Gaga said: "I don’t have permission to say anything about that".
She also winked at another reporter who asked her the same question. That's good enough for us.
The time is ripe for a Gaga return: her theatrical 2009 performance on the Other Stage went down a storm and she has promised a return to her avant-garde, absurd best after finishing a string of stripped-back live shows. In February, she astonished millions of television viewers with a bombastic performance during the Super Bowl Halftime show.
Kasabian – rumoured
They triumphantly closed the festival in 2014 and anyone who has seen Kasabian's live shows know the band is more than capable of handling a stage – and a crowd – of that size with ease.
But would they return to a headline slot so (relatively) soon after their last Glastonbury appearance?
It seems unlikely, but the band are thought to be releasing a new album in 2017 so they could pop up somewhere – even if it's on a smaller stage or in a different time slot.
Kraftwerk – rumoured
A summer of live shows + a conveniently shaped Glastonbury hole in the schedule = wild speculation.
Kraftwerk fans believe the band have inadvertently dropped their biggest clue yet that they will be playing the festival – by revealing something without actually saying anything.
The electro pioneers' UK tour conveniently ends just as the festivities kick off at Worth Farm. Which of course must mean they will be heading to Somerset shortly after. Maybe.
If they do put in an appearance, 2017 would be their Glastonbury debut.
Depeche Mode – rumoured
The band themselves responded to Glastonbury gossip by saying an appearance is not "out of the question" – but added a slot could be tricky in 2017 due to other appearances.
Still, while unlikely, they haven't officially ruled themselves out so they can remain on the list until we hear otherwise.