I forgive my boy's killers but I will never forget, says mother

Speaking for the first time since David's death, Grace Idowu told how she spent every day by his bedside until he lost his battle for life.

David, who was London's 19th teenage killing victim this year, was knifed in the chest following a football match last month. Despite having emergency surgery, the 14-year-old died of his injuries this month.

Today Mrs Idowu, 48, said: "I do forgive the people who did this to my boy but I will never forget. David's death has devastated this family. He was my youngest son and he was greatly loved by a lot of people.

"I was by his side every single day he was in hospital and I thought he would pull through. When he died a piece of us died too," she said.

Mrs Idowu spoke after leading a rally, accompanied by David's father Timothy and brothers James, 13, and Peter, 18, and hundreds of friends and relatives. The march began at the spot in Southwark where David was stabbed, to the doorstep of 10 Downing Street.

There they delivered a letter to the Prime Minister demanding action on knife crime - including tougher sentencingeffective rehabilitation for offenders, consultation with those affected by knife crime, and an annual day of prayer for peace across London.

Mrs Idowu, a supermarket worker, said: "People who kill with knives should get an automatic 30-year prison sentence. The Government needs to start taking this knife problem seriously. But parents and communities too have to take responsibility.

"There's nothing I can do to bring David back but I want to say this to young people who are carrying knives: throw them away, because they only destroy good, bright futures."

David was a student at Walworth Academy and wanted to become an aeronautical engineer.

His brother Peter, 18, said: "We were so close. I'm trying to be strong for my family, even though inside I'm devastated." The Southwark College student added: "Knife crime is out of control. There is no deterrent these days."

David was found critically injured behind student halls of residence in Great Dover Street on the afternoon of 17 June and was taken to the Royal London Hospital in Whitechapel.

He is one of 21 teenagers killed in London this year - 17 of whom have been stabbed. A 16-year-old has been charged with David's murder and is due to appear at the Old Bailey on 6 August.