After being diagnosed with cancer at 26, the singer turned to music at every stage of her treatment.

A video from the last day of chemo shows her singing of courage while wearing a hospital bracelet and Stand Up To Cancer t-shirt, head bare from rounds of chemo.

In the same period, she recorded what's called a vocal pack - 40 catchy dance hooks, known as toplines, bashed out in just two hours.

That pack was distributed by sample label 91Vocals on Splice, a website where DJs and producers can get royalty-free samples. Abi was paid about £75 for the pack and thought little more of it.

Fast forward four years - in which she was declared cancer-free, defying doctors' expectations, and had a baby despite being told she was infertile - and suddenly her voice was "everywhere".

One of the toplines had been picked up by DJ and producer Navos on his 2021 track Believe Me. The song went viral on TikTok and later went platinum.

But what seemed like an opening door just gave her a glimpse of the struggle female vocalists face for recognition and recompense in the male-dominated dance music industry.

Vocals from the pack kept "blowing up", Abi tells Sky News. In 2023, her voice was used in So Much In Love by D.O.D, which reached number 15.

But her name was nowhere near these hits and their success didn't equal money in her pocket.

A spokesperson for Splice told Sky News its business model "offers millions of samples royalty-free; this licence never requires the end user to credit the sample creator".

Abi agrees this was what she signed up to - but the spiralling fame of her voice made her struggle to break out on her own terms harder to bear.

The album she recorded on her "deathbed" lay unreleased as she grafted as a songwriter and tried to negotiate deals as a vocalist.

The success of the D.O.D track coincided with the worst paycheck for her other performing royalties she'd ever had.

"I wasn't able to pay rent that month," she says.

"I recorded these toplines when I had cancer, so they've got extra magic to it and yet nobody's interested, nobody cares, nobody wants to know the name.

"And it's not about [the DJs] being wrong for that at all, because they're not obligated, but it more speaks to the industry - and nobody wants to be the person that challenges the status quo."

'It's very much like a boys' club'

Abi's experiences were reflected in the Women and Equalities Committee inquiry into misogyny in music. It found women faced "unjustifiable limitations in opportunity, a lack of support, gender discrimination and sexual harassment as well as the persistent issue of equal pay".

There is a long history of women - and particularly black women - being "undervalued, unattributed and unpaid" in dance music, chief executive of the Featured Artists Coalition (FAC) David Martin tells Sky News.

Martha Wash, the voice behind C+C Music Factory's Gonna Make You Sweat (Everybody Dance Now), and Loleatta Holloway, the original voice on Ride On Time, were part of a wave of singers in the 1980s and 1990s who went uncredited.

Three decades later, things are improving, David says - but there's a long way to go.

With a long history of vocalists not being named, there's "a kind of legacy disrespect" for singers in the dance industry, singer Kelli-Leigh says.

She provided vocals for two 2014 number one hits - both uncredited: I Got U by Duke Dumont and Jax Jones, and I Wanna Feel by Secondcity.

Even after getting her name on 2017 top 10 hit More Than Friends with James Hype, she was frustrated to find "I was just staying in the same place - but all the men that I'd sung for were able to go up the ladder of success".

"Also in terms of being a woman of colour, the women that were being signed as well [were mostly white]. You start seeing these kinds of discrepancies which keep coming up and it's quite telling of the industry."

Kelli-Leigh says she also felt the burden of coming from a working-class background - to break into the industry, she had to do session work to pay the bills. But while those session vocals helped men's careers progress, she wasn't getting the same recognition.

"You just get to this point where you just get so fed up with it... It's very much like a boys' club, they're so excited to gas each other up but they will go so desperately out of the way to disrespect the singer."

She points out that producers and labels weren't strictly doing anything wrong when she wasn't credited. "They paid for a service and didn't want to feature a singer”, she says, so they got a session singer - her.

But, she says, she didn’t understand what the ramifications of that would be.

"I think there's a lot of grey area that you don't know about and that's where you feel the exploitation."

Charisse Beaumont, founder of Black Lives in Music, explains how this can play out.

Often vocalists will go into the studio expecting to just sing a chorus, but end up writing or arranging - and not getting credited or paid for that contribution, while the producer "goes around the world and he gets his number ones".

"[Black people] are the most exploited in the music industry for various reasons, whether it's from our economic background, where we reside or just for lack of knowledge, it's easy to exploit us in certain aspects, so it's up to us to understand what our IP is.

"Our advice is before you even go into the studio, get pen and paper out - and rather than write lyrics, write your contract."

'You've been erased - it's going to affect your mental health'

Being uncredited has knock-on effects financially and for career progression.

"If you have your name on a hit, the difference could be upwards of 30, 40, 50 grand of income," Kelli-Leigh explains - and it also increases the chances of getting more credited work.

Beyond that lies a huge impact on mental health, Charisse says.

"Do you know how distressing it is to hear your song at number one, and you're not getting paid for it?

"Or you're hearing your song played throughout Ibiza or on the radio and that DJ has a whole world tour booked and you're not on that tour?

"Or they release a video and it's a white girl singing your lyrics?

"You've been erased... It's going to affect your mental health, well-being and your confidence."

There's a word for producers profiting from the voices of black women when they won't use their faces or names, she says: "Exploitation."

It's something Aluna Francis has seen in the industry during her career as a solo dance artist and as one half of AlunaGeorge. While she hasn't been uncredited, she has been unacknowledged.

She contributed to five Grammy-nominated albums - but wasn't recognised in the award nomination for her work, because it was as a vocalist and songwriter, not a producer or engineer.

'Do you know the name of the artist you're listening to?'

There's a pervasive culture at every level of the music industry that sees singers as less valuable, Aluna says.

It's still seen as laughable to suggest a singer and songwriter would be the main artist on a track with a producer as a featured artist, she says.

"It's all to do with the leverage of perception that white male producers sell product and black female singers don't."

Her way of fighting that culture is by now refusing to be a featured artist and insisting on being equal collaborators.

"I'm trying to give that message to vocalists that that's not the only way they can be valued in this business."

Aluna says that when black women's voices are sampled, people are quick to celebrate a "light being shone on them".

"But ask yourself this: do you know the name of that artist that you're listening to? Because if you don't know the name of the artist, the light's not being shone on them.

"And if you're looking at the credits, can you see their name? Because if you can't see their name, then the light's not being shone on them.

"And ask yourself as producer, when you're downloading samples of vocals - are you hoping that you won't have to give credit?

"Is that love and respect, or is that exploitation?

"We can't be the ones to constantly call out this culture. People need to ask themselves what's their motivation when all of these vocals are being used. Like, are these people eating, for you to party?"

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Changing the industry from the inside

Changing the culture of dance music is the responsibility of labels, listeners and producers as well as vocalists, is Aluna's message - but the heaviest burden falls on those who wear most of the cost.

Abi and Kelli-Leigh's journeys followed similar years-long trajectories: producing uncredited work, seeing a lack of return - then cluing up on business knowledge and changing tack.

Kelli-Leigh "started going no, put my name on the record or you're not having it" and began self-releasing music on her independent label, including her forthcoming single Unconditional.

Abi created a vocal pack with producer Bobby Harvey, released on her terms, and also put out her first named major release with Ministry of Sound - Follow You, with Morgan Seatree.

Kelli-Leigh also teamed up with the FAC and Musicians' Union (MU) to develop guidance for session musicians and featured artists to help them make informed decisions about their rights so they are accurately credited and paid.

Education is crucial to changing the industry, John Shortell, MU's head of equality, diversity and inclusion, tells Sky News.

But changing how vocalists - particularly those from marginalised backgrounds - are treated involves diversifying the decision-makers, he says.

"I think we've got a long way to go before we start to see equity between female and male artists and black and white artists in terms of representation, and not just representation - power."

Progress is being made. Recent research by Women In CTRL looking at representation on UK music trade boards found 52% of board members were now women - up from 32% in 2020.

That's yet to translate to the artists' side, Kelli-Leigh says - but it shows change is possible.

Sky News contacted representatives for Navos, D.O.D, Duke Dumont, Jax Jones and Secondcity, but none had responded at the time of publication.

Asked about claims vocalists are not fairly remunerated, a spokesperson for Splice said the company "pays our direct contributors in an equitable fashion, regardless of their race, gender or ethnic origin".

They said as Abi’s contract was with 91Vocals, Splice did not have further insight into its terms. 91Vocals did not respond to a request for comment.