A 15-year-old Streatham girl has been found guilty of killing a "dirty paedophile" she said abused her and her sister.

The girl, along with her sister’s boyfriend – a 15-year-old from Clapham – kiled Robert Daley, 45, in his kitchen just an hour after they discovered he would not face prosecution for a string of alleged sexual assaults. He was stabbed five times, including twice through his heart.

At the Old Bailey today a jury found the girl guilty of manslaughter, while the boy was found guilty of murder.

During her trial the girl claimed Mr Daley also abused her from the age of 12.

Police had investigated claims of sex attacks on her 16-year-old sister and another woman but had dropped the case because of a lack of evidence.

The two killers. 14 at the time of the attack, went to Mr Daley’s flat in Ferndale Road, Brixton, shortly before 6pm on April 23 this year, after the elder sister telephoned them to say the police had dropped the case. Mr Daley had rung to tell her the news.

Jonathan Rees, prosecuting, told the Old Bailey jury the telephone call was the “catalyst that motivated them to pay him a visit."

The attack took place in the kitchen, where Mr Daley was stabbed twice in the heart.

During the trial, the boy, now 15, admitted stabbing Mr Daley. But both he and the girl told the court it was after Mr Daley abused the girl in front of him. He said he grabbed a knife from the sink and stabbed Mr Daley had gone to grab a knife as he tried to save her.

The pair are set to be sentenced on November 17.