The 17-year-old boy today sentenced to 24 months for his brutal sexual assault on student Ione Wells was not previously known to the police - and were it not for an extraordinary mixture of luck and some perceptive police officers he could still be walking the streets today.

With no prior convictions nor any cautions, the night of April 11 was the teen’s first attack.

The boy’s defence lawyer, Ms James, described him in court today as “emotionally and sexually immature”, adding: “Unfortunately, he is unable to provide an explanation [for the attack]. It appears to be something he did not think about, that was not premeditated. It’s something that he deeply regrets now.”

Never in trouble with the police before, and the attack coming seemingly out of the blue, any DNA recovered from Ione’s person or clothes that night would not have led to a match on the police database. The chances of identification were also slim as the attack took place in pitch black (in her statement to the court today, Ione described her attacker simply as “young and quite small”).

But quick action by police officers, along with a spot of luck, meant this dangerous young criminal could be captured.

The attack - which saw Ione’s head smashed against the pavement and her head kicked in - was interrupted when concerned neighbours heard her screams.

The teenage attacker fleeing the scene, police were called by Ione’s neighbours and her distraught mother, who awoke to her daughter’s shouts for help.

With the boy nowhere to be seen, officers – who already had to deal with three stabbings in Camden that night – quickly proceeded to check CCTV of the area. Trawling through the footage, they found what they were after - Ione walking from Chalk Farm tube station with her attacker in pursuit.

But what they weren’t banking on was what happened next.

After glancing at the live feed of the same CCTV camera, officers spotted the teen assailant again, in exactly the same place, and “following another woman”. He was promptly arrested and charged with sexual assault the same day of the attack.

Ione’s mother, Cindy Wells, told the Ham&High: “The police were just fantastic that night. They had already had They were compassionate, caring, efficient - and they caught the boy who did it.

“How they caught him was just amazing.”

Detective Sergeant Sonja Elshaw, from Camden CID, said: “This attack had such an impact on the victim - Ione Wells - that she recently wrote an open letter to the defendant.

“I applaud her bravery in doing so and emphasising that she and her local community will not stand for this type of deplorable behaviour.

“I am pleased the youth was quickly identified by police and at least admitted his crimes in court.”