London, England (CNN) -- On the fifth anniversary of the devastating London bombings, Britain's most senior anti-terror policeman at the time has said that the risk of a repeat attack by extremists is "as high as it has ever been."
The British capital was plunged into chaos on July 7, 2005, when four suicide bombers targeted three subway trains and a bus during the morning rush hour, killing 52 people and wounding hundreds more.
Two weeks later a copycat attack on the city's transport network failed after the bombs misfired causing no casualties. The failed suicide attackers were eventually captured and sentenced to 40 years in prison.
Survivors and relatives of those killed in the attacks gathered at a memorial in London's Hyde Park on Wednesday to mark the anniversary. A wreath from Prime Minister David Cameron was laid at the site, bearing the message: "In memory of the victims of terrorism in London on 7 July 2005. They will never be forgotten."
But former policeman Andy Hayman, who was responsible for counter-terrorism in the UK until 2007, says the risk of a similar attack in London remains high.
"That's the reality of it", he told CNN. "Five years down the line we've had other attempted attacks, we've put some people in prison for them, and we're not making the inroads we hoped for with the Muslim community to understand why people are being radicalized.
"So you tell me why we shouldn't be fearful? I think we should be."
John Reid, then Home Secretary, said the four July 7 bombers -- three British males of Pakistani descent and a Jamaican-born man -- were young "radicalized" Muslims whose motivation was "fierce antagonism to perceived injustices by the West against Muslims" and a desire to become martyrs.
It later emerged that two of the bombers, including ringleader Mohammed Sidique Khan, were trailed by security services for a year before the attacks, according to a report released last year by the Parliamentary Intelligence and Security Committee (ISC).
Entitled "Could 7/7 have been prevented?" the report said that domestic intelligence service MI5 considered Sidique Khan a "small time fraudster" and "minor criminal" and did not link him to potential attacks within the UK at that time.
Hayman's warning comes despite a £140 million ($212 million) strategy set up in 2007 by the British government to stop people becoming terrorists or supporting violent extremists.
"Prevent" involves gathering information about potential offenders at a local level, with cooperation between regional police forces, local authorities, schools, mosques and other community groups.
According to West Yorkshire Police, which polices the region of northern England where the July 7 bombers came from, the intelligence helps to identify young people deemed to be at risk of radicalization. Potential offenders are then given one-to-one "mentoring" sessions to steer them away from extremism.
"We cannot arrest our way out of terrorism," the force's assistant chief constable John Parkinson told the regional Yorkshire Post newspaper.
However counter-terror projects such as Prevent could be at risk after Hayman's successor as Scotland Yard's anti-terror chief, John Yates, warned of impending budget cuts by Britain's new coalition.
According to the UK's Guardian newspaper, Yates told a private gathering of UK police chiefs "eyewatering" cuts of £150 million ($227 million) to the anti-terror budget would endanger the public.
But Cabinet Office Minister Francis Maude hit out at Yates' "alarmist" comments. "I'd like to avoid public servants doing this kind of shroud-waving in public," he told the BBC.
"It's going to be pretty important for people who are managing big public services like police forces to focus on cutting out unnecessary costs, driving down costs, being as efficient as they possibly can before they even begin to contemplate talking about alarming the public in this kind of way."
But for one young British Muslim woman, who was herself radicalized after joining extremist group Hizb ut Tahrir at college, seeing the July 7 attacks for herself on television proved to be the high watermark for her radical beliefs.
"I think it was a wake-up call," Hadiya Masieh told CNN. "I was heavily pregnant with my third child when I was in the waiting room of the hospital watching the screen. I just felt like hiding. I wanted to distance myself from those people who created that atrocity."
She and her husband, who also belonged to Hizb ut Tahrir, now work to foster better relations between faiths. In her latest project she helped set up a screening of a movie she hopes will break down barriers. The film, "Arranged," depicts a blossoming friendship between a Muslim woman and an orthodox Jewish woman.
"At the end of the day, if we have an understanding of each other I think this will eradicate any feelings of animosity and hatred."
CNN's Paula Newton contributed to this report.