This is the moment a man believed to be the Huntingdon train attack suspect stormed into a Peterborough barber shop with a knife - as police investigate whether he stabbed a 14-year-old boy minutes before.

Anthony Williams, 32, of Peterborough, appeared at Peterborough magistrates' court today charged with 11 counts of attempted murder in connection with a knife attack on board an LNER train and another in east London on November 1.

CCTV footage exclusively obtained by the Daily Mail allegedly shows a man believed to be Williams entering Ritzy Barbers, in Fletton, Peterborough, on Friday evening at 7.14pm - minutes after police were called to the stabbing of a 14-year-old in the city centre.

Barber shop staff then called police around 90 minutes after he left - but Cambridgeshire Constabulary did not send officers, instead asking the shop to upload CCTV online.

Barber Cody Greene, 23, told the Daily Mail the same man returned to the shop at 9.25am on Saturday November 1. Police were called again, but by the time they arrived the man had left.

This happened around 10 hours before prosecutors allege Anthony Williams began his train rampage, and more than eight hours after the 32-year-old allegedly stabbed a man at a Docklands Light Railway (DLR) station in the capital early that morning.

Police have today launched a probe to establish whether the three incidents in the city before the alleged rampage are linked - and are facing accusations that they could have thwarted the attack had they acted quicker. 

'Even though we called the police, I feel guilty because it could have been prevented if action had been taken,' Mr Greene said.

'They have cameras everywhere, they [the police] have seen what this guy looks like. He has then walked past this shop again. It [the train attack] definitely could have been prevented.'

Cambridgeshire Constabulary says it is 'aware' of the incidents and is reviewing others around the same time to understand if other offences were committed. The Home Secretary vowed today that questions about the attack 'will be answered'.

Footage reviewed by the Daily Mail shows the man outside Ritzy at around 7.14pm on October 31. Workers said he was mumbling 'It was feds, it was feds' to himself before attempting to walk inside and sit down.

He was asked to leave, but returned a short time later with a plastic bag, appearing to turn his face away from the road as a police car drives past.

At 7.25pm, he starts to rub his face, takes a sip of a drink and yells, 'f*** your mum' and 'liars', as he suddenly brandishes the knife and walks inside. 

In terrifying scenes the man, dressed in black with his hood up, then waved the implement about as customers ran to the back of the shop. 

One customer was said to have been so frightened he barricaded himself into a kitchen at the back of the shop and began to pray. 

Staff say he then demanded to know why customers had been laughing at him. 'I'm going to allow you lot today', he is then alleged to have said, before leaving the shop at the behest of staff.

Barber Mr Greene, 23, added: 'I looked in the mirror on my side and I've seen him go with the knife in his hand, about to open the door.

'At that moment, the only thing I'm thinking is "I've got to protect myself and my client", so I tried to grab my client - all it takes is one or two steps and he could have cut my client's neck.

'Everyone started to see what's going on and moved backwards and it was just so quiet, the only thing we could hear was him.

'I could hear him saying "you're laughing at me?" and "suck your mum" and "I'm going to catch a case today" and "you're drawing me out" - he was speaking for like 20 to 30 seconds.

'Then he said "I'm going to allow you lot to today" - when I heard that I started counting my graces. One of the clients locked themselves in the kitchen, he was really distressed and we couldn't actually get in there.'

He added of the man he was confronted with: 'It seemed like the lights were on but no-one’s home. You looked at him and you knew straight away, it was a red flag.'

When the management of the barber’s shop phoned the police that night, they were told no officers would be deployed and they were instead asked to upload their CCTV to an online portal.

Just minutes before, police had been alerted to another incident in which a 14-year-old boy was stabbed in Peterborough city centre. 

Police say the teenager was taken to Peterborough City Hospital with minor injuries and later discharged. 

Forensic officers were sent to the scene and an investigation was launched, with officers conducting a search aided by police dogs. They failed to trace the attacker.

Filomena Campanaro, who is married to one of the barbers and lives directly next door to Ritzy, told the Daily Mail she then saw the same man near the shop the next morning shortly after 9am on November 1, as she walked her dogs.

She had watched the CCTV of the incident the night before and recognised him, adding: 'I didn’t hear a word he said but he leant down and started touching my dogs.

‘I started shaking... my heart just wanted to fall out on the ground. He had dirty trousers, a black tracksuit, a black jacket. He was drinking from these little bottles.

'I was thinking “has he got a knife?” but he walked straight by me and when I got round the corner I ran all the way round the block and told my husband. I feel distraught, I feel absolutely sick - I could have been stabbed.'

At 9.16am, the man was captured on CCTV glancing inside the shop before being chased away by workers who recognised him from the night before.

Barber Mr Greene added of the man: 'I thought when I saw him he’s come back to finish the job. He must have seen how many people were in the shop and got put off by it, because the footage shows he was definitely making his way to the door.

'I was terrified, even now, my anxiety levels were through the roof. I thought my life was really in jeopardy, my heart was in my stomach.'

Cambridgeshire Constabulary says it sent officers within 18 minutes of being called. CCTV reviewed by the Daily Mail shows two unarmed officers climbing out of a marked squad car to speak to witnesses.

Hours later, Anthony Williams is alleged to have boarded the Doncaster to London King's Cross train at Peterborough before, prosecutors say, attempting to kill 10 people on board.

Cambridgeshire Constabulary has voluntarily referred itself to the Independent Office for Police Conduct (IOPC) in connection with the incidents.

It said in a statement: 'We are currently reviewing all incidents in the timeframe to understand whether there were any further potential offences.

'British Transport Police retain primacy for the overall investigation, which will include these three incidents.

'We voluntarily referred ourselves to the IOPC for independent scrutiny of these incidents, as is standard practice in these cases.'

Speaking in the Commons on Monday afternoon, Home Secretary Shabana Mahmood vowed to investigate whether the attack could have been prevented.

She said: 'I know this House, and the public, will have many unanswered questions today about who this attacker was and about the events that led up to the attack.

'Those questions will be answered, but it will take time - the police and prosecutors must be allowed to do their work.'

Williams appeared at Peterborough magistrates' court today wearing a grey sweatshirt and tracksuit bottoms. He was in handcuffs, accompanied by four prison officers.

The defendant has been charged with 10 counts of attempted murder and one charge of possessing a bladed article in connection with the incident on board the 6.25pm LNER train travelling from Doncaster to London King's Cross on November 1.

He also faces additional charges of attempted murder and and possessing a bladed article after a passenger was stabbed at Pontoon Dock DLR station in east London shortly after 12.45am on November 1.

It is alleged the victim suffered facial injuries after being attacked with a knife.

The court heard he had also been charged with assault occasioning actual bodily harm after allegedly attacking a police officer as he was brought into custody, breaking an officer's nose.

Williams spoke only to confirm his name and address during the six-minute hearing, mumbling to the court that he was of no fixed abode.

Documents allege that he used a 'large kitchen knife' in both incidents. No application was made for bail.

Before Williams was brought into court, the judge granted an application for him to appear in cuffs after it was heard he allegedly assaulted an officer upon his arrest.

Opposing bail, prosecutor Olaide Esan told the hearing: 'The defendant has attempted to murder 11 people in total.

'These are serious allegations. These are very serious offences. The defendant is a risk to the trains and to the members of the public.'

District Judge Kenneth Sheraton remanded Williams in custody and adjourned the case for a further hearing at Cambridge Crown Court on December 1. 

It is understood Williams was not known to the security services or counter-terrorism policing, and had not been referred to the Government anti-extremism scheme Prevent. 

Saturday's attack saw brave train staff and passengers intervene in a bid to stop the alleged attacker as he went through the train with a knife.

Passengers ran through the carriages, barricading themselves in toilets and behind the shutters of the onboard shop in the buffet car in a bid to protect themselves.

Driver Andrew Johnson - a veteran of the second Gulf War - frantically worked with Network Rail staff to arrange for the LNER Azuma to make an emergency stop at Huntingdon station in Cambridgeshire.

Deputy Chief Constable Stuart Cundy of the British Transport Police said: 'The criminal investigation and support for the victims is a priority.

'Our investigation is also looking at other possible linked offences.'

Security has been ramped up at train stations in the wake of the attack. The LNER Azuma train involved left Huntingdon station this morning; the station itself is closed until the end of the day.