A woman listened on a phone as her ex-boyfriend brutally murdered a mum-of-three he had picked up in a pub, a court heard.

Reece Ludlow, then 18, stabbed and beat Louisa Brannan, 35, to death in his flat in Oakwood Court, Sutton, in a violent assault in the small hours of March 14 last year, Woolwich Crown Court was told.

The jury heard his ex-girlfriend Fon Promsan - who he had called over a period of three hours during the incident - could hear the 35-year-old beg for her life on the other end of the line.

She described his manner as "cold and evil".

Hours after the first phone call, at 6.45am, paramedics found miss Brannan's naked body in the bathroom of the blood-soaked flat, in Benhill Wood Road, the court was told.

Mr Ludlow and Miss Brannan had gone to his flat together after meeting earlier that evening in the Kings Arms pub, in Mitcham.

Adrian Derbyshire, prosecuting, said: "Once they were back at the flat there was some kind of sexual contact between them.

"Not long after that she was subjected to a brutal attack that led, after some hours, to her death in the flat.

Mr Ludlow called Miss Promsan, who had split from him earlier in the year after he had shown aggressive and violent behaviour, over a period of three hours, the court was told.

Mr Derbyshire said: "On the phone, speaking from the flat, he began to describe what he had done.

"She (Miss Brannan) could be heard crying for help, literally begging for her life. Nothing was done to help her."

He said: "There's no question he intended to kill her and cause her serious harm."

Mr Ludlow admits the killing but denies murder, stating his mental state at the time of the attack gave him dismished responsibility.

If he is found not guilty he will be sentenced for manslaughter.

Members of Miss Brannan's family wept in court as the disturbing details of the attack were read out.

Mr Derbyshire said the crime scene in the blood-soaked flat was "particularly unpleasant".

The kitchen and bedroom doors and walls were blood stained, while the bathroom was covered in blood.

A bloody, serrated knife and a frying pan covered in hair and blood were found in the kitchen. Another knife was found on the floor.

All are consistent with being used in the attack.

The court was told the first phone call to Miss Promsan came at about 3am.

Mr Ludlow was crying as he told said "baby, I've done something really bad", the court was told.

When she asked him if he had stabbed the girl he said "yes, she's in the kitchen and there's blood everywhere".

Mr Derbyshire said: "He said he had stabbed her with a little black knife. He said she was bleeding from the neck, back, arms and legs".

A post-mortem gave Miss Brannan's cause of death as multiple stab wounds. Blunt trauma was also found to the side of her temple.

Miss Promsan, who had heard Miss Brannan cry out "I'm dying", said Mr Ludlow's manner on the phone was "cold and evil".

Miss Promsan had told him to treat her wounds. At one point he demanded she get in the bath, calling her names using bad language.

He had refused her cries for help because he was afraid she was going "to grass", the court was told.

The jury heard he had told Miss Promsan he had harmed the mum-of-three because she had called his mum a bitch.

The prosecution gave no obvious motive for the attack, but said Mr Ludlow had been struggling to come to terms with his break-up from Miss Promsan.

He later rang her to tell Miss Promsan she was dead.

He told her: "Come and help me, you will make it better, just come and see me, I only want to be with you, that's all I want", the court heard.

He had called his mum and admitted what he had done.

She called police and arrived at the flat with his grandmother, but he had already fled.

Mr Ludlow, now 20, evaded police and was picked up after a major police manhunt six days later, drunk on a train in Victoria station.

He refused to answer questions in the police interview, after which he was charged with murder.

The case continues.