A have-a-go hero chased a blade-wielding robber through Stevenage as he made off with a bag he had snatched.

Despite robber Michael Straight repeatedly trying to attack the man during the chase on foot, his pursuer refused to give up.

In the end, hero Jacek Czarnecki directed police to an Old Town alleyway where 30-year-old Straight was arrested.

At St Albans Crown Court today, Judge Stephen Warner jailed Straight for two years – and commended Jacek for his bravery.

Highlighting the seriousness of the crime, the judge told Straight: “I would be failing in my duty to the public if I didn’t impose a custodial sentence.”

Straight, who was living rough in Stevenage, pleaded guilty to robbery and having an article with a blade or point.

Prosecutor Neil King told the court how, at about 5.50pm on August 16, Jacek and a female companion were using outside gym equipment near Stevenage’s swimming pool when Straight approached from a nearby car park.

He appeared to be talking to himself as he walked past, but then approached holding what looked like a knife.

Raising it threateningly above his head, he snatched the woman’s bag – then tried to attack Jacek before running off.

Mr King said Straight hadn’t reckoned on the bravery of Jacek – who gave chase, telling passers-by to call the police.

As Straight made his way towards King George V Playing Fields and through the Old Town, he tried to attack Jacek with his weapon, which turned out to be a metal tool-like object with a sharpened point. To his victims it would have looked like a knife.

The chase took them into Sish Lane, where Jacek saw a police patrol car and directed the officers to a cut-through alleyway where Straight was arrested.

The court heard that Straight suffered from mental health issues and had 42 previous convictions. At the time of the offence, he was on bail for a criminal damage offence.

Alex Britton, for Straight, told the court his client was affected by schizophrenia and was on the autistic spectrum.

He had been abusing drugs and alcohol and had stopped taking his medication. Mr Britton said he had been drinking on the day of the crime in an attempt to self-medicate.

The court heard he had been homeless and living on the streets since May, resulting in his being picked on and assaulted by youths.

Straight was remanded in custody after being arrested and the court was told that he was now determined to stop drinking and to engage with mental health services.

After the sentencing, Det Con Trudi Howell from the Stevenage local crime unit saluted Jacek as “incredibly brave”.

She added: “Hopefully Straight will put his time in prison to good use by working to overcome his drink and drug problems so that he can go on to live positively.”