David McKelvey, of TM Eye, which runs My Local Bobby, said: “A couple of members of the public saw what he was doing and leapt on him.
“My guys Youssouf and Daren were called, and were there in seconds. They detained him until police officers arrived about 30 seconds later. By this point the victim had been taken into the M&Ms shop, where they locked the doors behind them.”
Mr McKelvey, a former Scotland Yard detective chief inspector, added: “Everyone responded very quickly. From the moment the incident broke out to the moment that the suspect was arrested was just a couple of minutes.
“The police were very professional and did a fantastic job with looking after the victim and administering first aid.”
My Local Bobby is part of the TM Eye operation, which provides uniformed staff and plain clothes detectives who patrol shopping areas for the local retailers.
Its “bobbies”, uniformed with magenta vests and caps, provide 24/7 cover for up to 250 houses and businesses on each beat. It promises to have a response at the scene within five minutes, for a fee per customer.
Ioan Pintaru, 32, of no fixed address, was later charged with attempted murder and possession of a bladed article. He was remanded in custody to appear at Westminster magistrates’ court on Tuesday morning.