Wealthy London couple charged with murdering their nanny, burning her body

Sophie Lionnet was allegedly murdered. Photo / Facebook

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The ex-girlfriend of an Irish pop star has been arrested at her £900,000 (NZ$1.65m) London apartment and charged with murdering her French nanny before burning her body in the back yard.

Sabrina Quider, 34, had hired Sophie Lionnet, 21, to look after her children - including a son she had with ex-boyfriend Mark Walton, who founded Irish boyband Boyzone - allegedly paying the live-in nanny just £50 (NZ$91) a month.

But on Wednesday (local time), police discovered Lionnet's badly burned body in Quider's garden - after they were alerted to the grisly scene by an eight-year-old boy, Daily Mail reports.

Sabrina Quider has a son with ex-boyfriend Mark Walton (right), a founding member of pop band Boyzone, as well as a daughter. Photos / Facebook

Local parents had noted "foul-smelling smoke" emanating from Quider's home, in the affluend South London suburb of Southfields, as they took their children home from school on Wednesday.

But it was one curious boy who raised the alarm after he scaled the apartment's back yard gate and saw a huge bonfire with a man throwing what he thought were "sticks" on the flames.

Officers arrived at 6.30pm (local time) and discovered a body that was so badly burned they could not establish her age or even gender.

However, the victim was identified by local residents as Sophie Lionnet, 21, a nanny from Troyes, a town in north-eastern France.

Quider was arrested at the scene along with Ouissem Medouni, 40. Both have now been charged with murder.

Lionnet, who moved to the UK to learn English, is thought to have been living with Quider at her flat for 14 months caring for her three-year-old daughter, and the six-year-old son she had with Walton.

Quider and Walton are separated; he now lives and works in both Los Angeles and Vietnam.

Locals said that Lionnet had to work long hours to care for the two children, while Quider, who claims to work as a stylist, make-up artist, fashion designer and songwriter, had been enjoying a busy social life.

On social media, the French-Algerian mother posed for glamorous pictures on nights out at various restaurants.

And although she "had a lot of money," neighbours said, Quider paid her nanny just £50 ($91) a month.

One friend of the victim said: "She came here to learn English, but found it very difficult here.

"Sabrina liked her social life and liked going out with her friends. There always seemed to be plenty of money.

"She has had Sophie, who is from a poor French family, living in her little home for 14 months.

"Sophie had been unhappy for a long time - so unhappy she left to stay with one of her few friends for two nights last month.

"She had finally decided to go home though, and had just asked her mum to send her £40 (NZ$73) so she could afford the fare.

"She was supposed to have gone back on Monday. She never arrived. Sabrina was always a real party girl, out smiling with friends. She was very different with Sophie at home."

The friend added: "The father of [Quider's] son left some time ago and she has a new boyfriend, who is also French Algerian. It was him who introduced Sabrina to Sophie."

Neighbours were horrified. One woman, who did not want to be named, said: "I was walking past on the way home from school and we could see flames through the fence posts.

"My young son called out, 'If you are having a barbecue, are we allowed to come?'

"I told him, 'no that's not a barbecue, that's a bad smell'. I thought they may be burning leaves."

Sophie Lionnet never made it back to France. Photo / Facebook

Another resident said: "We saw smoke and there was a foul smell. My son was being a bit cheeky and he climbed up the fence to look over and he saw a man sweeping up what we thought were sticks and putting them on the bonfire."

A woman living opposite said: "It definitely did not smell like a barbecue so I could not think what they were burning."

A man living in the top floor apartment of the converted property said he had complained to the landlord about a "gassy smell".

He said: "The couple who lived in the flat were not the friendliest pair - we would hear them having really loud arguments below."

A body bag was driven from the scene in a private ambulance, while forensics officers continued their work.

Detective Inspector Richard Leonard said: "I would like to appeal to those in and around the area to come forward with information."

Quider and Walton split some time ago; he now lives in Los Angeles, working as an International A&R Consultant, according to his LinkedIn page.

He is also one of the judges on the Vietnamese version of Pop Idol.

Walton says he is a co-founder of Boyzone, having put together the band in 1993 while still a teen before meeting future manager Louis Walsh and "[asking] him to get involved."

"I was the lead singer," he told The Irish Sun in May last year.

"The boys felt it was my band and there were articles written about this 15-year-old boy who had put this band together.

"Then these articles would start appearing with photos of Boyzone and an X over my face and quotes saying I had been 'X'd' out of Boyzone."

Afterwards he went on to found another pop group, 5th Avenue, and to manage boyband Blue after their reformation in 2011.

Walton now says that he is a billionaire with a desire to combat issues such as homelessness child trafficking in Ireland and LA.