So said Jarvis Cocker as he addressed the enormous crowd at Glastonbury's Park stage in 2011; thousands and thousands of people stood in front of him to see perhaps the worst-kept secret in the festival's history, and one of its greatest live music experiences.

The speculation that the then newly reformed Pulp would play the surprise set that day - after Radiohead the previous day, no less - had grown so intense that latecomers reportedly had to be turned away, such was demand.

Beyonce, Coldplay and U2 headlined that year, but like many squashed in the Park Stage audience, squelching in the mud, it was the magic of singing along to Do You Remember The First Time?, Something Changed, and Common People I remember above everything.

Over the years, artists including The Killers, The Libertines, Lady Gaga, Foals and Franz Ferdinand have also popped up "unannounced" at Glastonbury. Last year, an act supposedly called The Churnups, conspicuous by their late-evening Pyramid Stage slot despite being an unknown entity, turned out to be The Foo Fighters.

The festival is famous for its secret sets, surprise guests and big names appearing in unexpected places, so while Dua Lipa, Coldplay and SZA headline this year, it is the TBA slots that may well provide some of the most memorable moments.

One person in the know is the founder of @secretglasto, a Twitter account which launched 10 years ago and now has almost 80,000 followers and a small team of six keeping the updates going. They have no official ties to the festival, but over the years have cultivated their sources - from people working on stages to sometimes even acts themselves - so they are "90% confident" about whatever they hint at.

"There's also people that have been good at [revealing] what acts are playing before the line-up comes out," says the Secret Glasto founder (we'll call them SG). "So you can take their word a lot more seriously because they have some way of knowing what's going on - even if you don't know the specifics as to how they get that information, you can see the track record."

When it comes to favourite secret sets, SG names Drenge and Wolf Alice, but says it's "hard to look past The Killers", who turned up in 2017 - 10 years after headlining for the first time, and two years before returning to headline again.

"The Killers in a tent, that's something you feel it would only ever happen at Glastonbury. Compared to most of our secret set rumours we heard that one very late and personally I was very nervous by it, but also we had no other names in the frame. The relief when Frank Carter mentioned it was The Killers after him was palpable!

"So many people I have met since that show have been really thankful because they wouldn't have gone [without the Secret Glasto tip] because a lot of them actually liked acts playing elsewhere at the time... why would you go to a secret set you don't know if you've got eight out of 10 options elsewhere? The Killers to everyone was a 10 out of 10 option."

With the potential for people to miss other brilliant acts based on the hints of their anonymous account, SG says they do feel a sense of responsibility, especially as the number of followers has grown.

"Quite a lot of the time for these secret sets, to get a good spot you're [at the stage] for an entire set before. And you're missing other things that you would love to see. So it is a big responsibility to make sure that we're right about our info. There have been some secrets we just haven't tweeted because we didn't know who it was."

For many Glastonbury-goers, the account has become a go-to place for reliable hints about the unnanounced acts set to play. There are a few TBA slots on the line-up this year - the biggest of which is set for the Woodsies Stage at 6pm on Saturday.

The bookies' favourities include Liam Gallagher, fresh from his Definitely Maybe anniversary tour dates; Kasabian, who would mark 10 years since they headlined in 2014; and Pulp, as Cocker will already be on site to perform in the small Stonebridge Bar with Hot Chip's Alexis Taylor on the Friday. Other names bandied about include Harry Styles, Green Day, Charli XCX and, um, Taylor Swift, who's set to perform her Eras tour shows in Dublin on the Friday, Saturday and Sunday night, so seems pretty unlikely.

SG is not revealing anything yet, but says Pulp, Kings Of Leon, Kasabian and Charli XCX are among the main acts rumoured.

As well as the Woodsies TBA, SG also says there will be some other "big surprises around the site doing some very small slots".

However, they won't mention where. "I don't even want to mention the stages because I know how skittish some of those areas can be. I know in 2022, there was going to be a stage headliner from one of the recent years playing a very small slot that got canned quite last minute. So yeah, quite hesitant to to reveal more than that, but we have heard of some very interesting things."

After 10 years of revealing Glastonbury's secrets, what has SG learned about why the surprise acts have become such a special part of the festival?

"I think it's just the fact all these acts have decided the money [doesn't matter], and their egos don't need placating," says SG. "You've got some acts who would just be like, if we're not a headliner, no matter what the money is, we would not play a certain slot."

Glastonbury's secret acts are there purely to put on something fun for the fans, SG continues. "It creates such a different atmosphere. A lot of the secret sets are bands that feel like Glastonbury helped their careers in some way, and it's their way of sort of giving back.

"Unlike other British festivals, I think Glastonbury cultivates more of a 'we go every year, regardless' mentality. So these acts can feel like the people that supported them at, say, a previous slot that went really well for them will still be there, or at least a sizeable number of them will still be there, to enjoy the secret set they do down the line."