A woman who attacked her 12-year-old son with a kitchen chopper for returning home late from school was put on probation yesterday. Lam Kwai-lin, 55, had pleaded guilty to one count of assault by those in charge of a child. The defendant twice expressed regret yesterday for what she did to her son - whose name was not mentioned - when acting Principal Magistrate Don So Man-lung asked if she wanted to be put on probation. "I very, very much regret it," Lam, who was not represented by a lawyer, said in Kwun Tong Court. So - who, in early hearings, described the case as serious - imposed a 15-month probation order on the woman and told her to treat her child well from now on. Lam nodded her head and replied: "Yes, yes, yes." The attack took place on the evening of May 19. The court had previously heard how Lam, furious at her son's late return, confronted him with the chopper at their home in Shun Tin Estate in Kwun Tong. The boy was left with a 5cm-long wound on his right arm as a result of the assault. The mother told the court earlier that she had intended to use the back of the blade to hit her son to serve as a warning. She said she had no intention of hurting him. But when the boy's arm started bleeding, Lam realised she had used the wrong side of the blade. She told the court that she hurt him by mistake. The boy was sent to hospital. At school later he told his teacher what had happened and police were called. In mitigation the woman had promised never to use force on the son again. She also said the attack was a result of misfortune. But So said the case was serious even though the boy's wound did not require stitches. The magistrate said it was worrying that Lam could not recognise the sharp edge of the blade. The boy was put under custody in an emergency care home by the Social Welfare Department after the assault.