The ex-girlfriend of an Irish pop star has been arrested at her $1.2m (£900,000) 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 $63 a month.

But on Wednesday, 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. 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 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. 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,' neighbors said, Quider paid her nanny just £50 ($68) 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 ($54) 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. Neighbors 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.