The enigma surrounding Lily Allen’s latest album has captivated the curiosity of her vast fanbase since its release on Friday: the identity of Madeline remains unknown.

With the arrival of “West End Girl,” Lily Allen’s latest work, listeners are given an intimate glimpse into the tumultuous end of her four-year marriage to David Harbour, famed for his role in “Stranger Things.” The album’s sharp lyrics focus heavily on his unfaithfulness, bringing attention to a mysterious affair.

Rumors of infidelity had circulated, but the extent of the betrayal becomes evident in a track intriguingly titled “Madeline,” where the 40-year-old singer lays bare her feelings.

The song’s brutally honest words make it clear: ‘Madeline’ is the name of the woman involved with Harbour during his marriage to Allen.

The lyrics describe how Lily confronted this woman through text, asking bluntly, “How long has it been going on? Is it just sex or is there emotion?”

Fans have flocked to social media in droves, eagerly questioning the identity of Madeline, echoing Lily’s own lyrical inquiry: “Who the f*** is Madeline?”

It immediately drew comparisons with a track on Beyonce’s 2016 album Lemonade, which launched worldwide speculation about the identity of ‘Becky with the good hair’ – a woman who allegedly had an affair with Jay-Z.

And while Lily has been at pains to point out that Madeline is, just like Becky, a pseudonym, it has prompted a similar hunt for the real woman who inspired the song and several others on Lily’s rage-filled album, her first in seven years.

But today, that hunt is over. The Mail on Sunday can exclusively reveal the identity of ‘Madeline’ as costume designer Natalie Tippett.

Lily Allen and David Harbour at the 2022 Met Gala. The pair married in 2020 and announced their split in January this year

The 34-year-old single mother, who lives in New Orleans, spoke to this newspaper from her home in the city’s historic Treme district to admit that she was the woman at the heart of Allen’s new album – and at the centre of her marriage break-up.

But blonde Ms Tippett was reluctant to hit back, or to turn her sex life into a public debate.

‘Of course I’ve heard the song,’ she said, rolling her eyes.

‘But I have a family and things to protect. I have a two-and-a-half-year-old daughter, and I understand this is going on.

‘It’s a little bit scary for me.’

It is understood that Ms Tippett met 50-year-old David Harbour, who is 16 years her senior, while filming the Netflix movie We Have A Ghost in 2021, on location in New Orleans.

Harbour was the movie’s leading man, while Ms Tippett worked in the costume department.

Their affair reportedly began shortly after shooting started.

Natalie Tippett, right, pictured in 2010. It is understood she met Harbour on the set of Netflix movie We Have A Ghost in 2021, where she worked in the costume department

Harbour had married Lily, who has two daughters, Ethel, 13, and 12-year-old Marnie from her previous marriage to Sam Cooper, in Las Vegas the year before.

Even after filming ended, Harbour reportedly flew Ms Tippett to his home in Atlanta, Georgia, as the affair continued behind Allen’s back.

But his secret fling was exposed when Allen saw an incriminating text message on his mobile phone, and as her marriage fell apart she turned her heartache into music.

In the song Tennis’ on her new album, Allen sings of coming home to find a sexual text on her partner’s phone.

‘So I read your text, and now I regret it,’ she laments. ‘I can’t get my head round how you’ve been playing tennis. If it was just sex, I wouldn’t be jealous. You won’t play with me and who’s Madeline?’

In the song Madeline, Allen even changes her voice to mimic Ms Tippett’s, insisting that her relationship with Harbour ‘has only ever been about sex. I can promise you that this is not an emotional connection.’

Ms Tippett spoke to this newspaper from the living room of her historic clapboard home, which is decorated with glowing neon signs and elegant furnishings.

Her toddler daughter bounced around the room happily in a rainbow-coloured tutu.

Natalie Tippett, left, pictured in 2013. Harbour reportedly flew Ms Tippett to his home in Atlanta, Georgia after filming ended

She nods sadly when asked if she knew her private text messages were being used in the lyrics of Allen’s songs.

‘Yeah,’ she sighed. ‘I just don’t feel comfortable talking about it at the moment.’

Allen and Harbour announced their split in January after just over four years of marriage. It is understood they separated in December, and that Lily spent Christmas alone with her children in Kenya, 3,000 miles from David.

Speaking on her Miss Me? podcast with her long-time friend, presenter Miquita Oliver, that month, she admitted that she was taking ‘time out’ and was struggling with panic attacks.

She said: ‘I’m finding it hard to be interested in anything. I’m really not in a good place. I know I’ve been talking about it for months, but I’ve been spiralling and spiralling. It’s got out of control. I can’t concentrate on anything except the pain I’m going through. It’s really hard.’

A source claimed that Allen was ‘devastated’ and had reportedly checked into an £8,000-a-week trauma treatment centre after telling friends she was close to a nervous breakdown.

She also gave an interview to British Vogue this month in which she discussed how hard it was not to rely on ‘drugs and alcohol’ to get through the split.

The singer, who has been sober for five years, admitted in an interview that her addictions had been so bad that she couldn’t remember ever having ‘sober sex’ until her relationship with Harbour. She said her earliest memories had involved drink and drugs, and that she had watched her father, the actor Keith Allen, snort cocaine.

Lily Allen and best friend Miquita Oliver at the ‘West End Girl’ album launch dinner yesterday

Referring to the split with Harbour, she told Vogue: ‘The last time that I felt anything like that, drugs and alcohol were my way out, so it was excruciating to sit with those [feelings] and not to use them.’

Meanwhile Harbour, asked about the split by GQ magazine in April, declined to reveal much, saying it would encourage ‘a salacious s***-show of humiliation’.

The Mail on Sunday reported earlier this year that Lily had turned detective after suspecting David of cheating.

Allen’s circle of London friends said the singer had believed since last autumn that her husband was interested in other women.

The couple, who had met on the celebrity dating app Raya, had disabled their profiles following a whirlwind romance.

But Lily decided to re-join the app to check on her husband’s activity – and discovered he had a secret profile which had been active for around a month.

In it, he describes himself as ‘visiting New York from Atlanta’ and a ‘closet nerd that plays tough guys on your TV’. His profile song is listed as the Houses Of The Holy by Led Zeppelin.

A source said at the time: ‘Lily was looking for women that were on Raya and cross-referencing them with women David follows on Instagram to try to figure out who he was seeing.’

By the time the couple broke up, however, she had become convinced that he had a secret girlfriend, which later proved to be correct.

The source added: ‘Lily has never even looked at anyone since she met David. She is devastated.’

Harbour shared a townhouse in Brooklyn, New York, with Lily and her children after the couple moved there in 2020. She had enrolled her daughters in local schools.

Harbour also bought a home 800 miles away in Atlanta to be closer to the Stranger Things filmset, where he was filming the fifth and final series last year.

Since the split, Lily has moved back to London and has bought a ex-council flat in a building near where she grew up.

She said: ‘I have wanted to live in this building since I was a baby, it’s been a dream of mine forever and finally a flat became available in here and I was in a position to buy it and I did.’