(CNN) A police officer beheaded in broad daylight on one of the most solemn days of the year, as thousands of people gathered to pay tribute to the sacrifice of soldiers in past wars.

It's a grisly crime that -- if carried out -- would have shocked Australia to its core. And it was plotted by a schoolboy on the other side of the world.

Britain's youngest terror mastermind has been jailed for life for orchestrating the beheading, which was to have been carried out during a parade in Melbourne on Anzac Day -- a national holiday honoring the country's war dead -- in April this year.

The boy, who admitted directing the jihadist plot and encouraging others to take part, was just 14 when he planned the brutal slaying. He cannot be identified because he is a minor.

Detective Chief Superintendent Tony Mole, head of England's North West Counter Terrorism Unit, said the boy's role was "quite shocking," considering he was "extremely young."

Photos: Remembering Anzac Day, 100 years on Photos: Remembering Anzac Day, 100 years on Britain's Queen Elizabeth lays a wreath during a service to commemorate Anzac Day and the centennial of the Battle of Gallipoli at the Cenotaph war memorial in central London on Saturday, April 25. A century ago, Allied troops came ashore at Gallipoli in modern Turkey at the start of an ill-fated land campaign to take the Dardanelles Strait from the Ottoman Empire. The disastrous World War I battle began on April 25, 1915, and pitted troops from Australia, Britain, France and New Zealand against the Ottoman forces backed by Germany. Hide Caption 1 of 12 Photos: Remembering Anzac Day, 100 years on New Zealand Defense Minister Gerry Brownlee and Australian Foreign Minister Julie Bishop observe the centennial of the WWI Gallipoli campaign at Polygon Wood in Zonnebeke in Ypres, Belgium. Hide Caption 2 of 12 Photos: Remembering Anzac Day, 100 years on Indigenous dancers lead the parade through Redfern toward Alfred Park as part of the Redfern Aboriginal Anzac Day Commemoration in Sydney, Australia. The day is named for the Australian and New Zealand Army Corps, which suffered heavy losses during the protracted Gallipoli campaign. Hide Caption 3 of 12 Photos: Remembering Anzac Day, 100 years on A large crowd gathers around the eternal flame for the 2015 dawn service on Anzac Day at the Shrine of Remembrance in Melbourne, Australia. Hide Caption 4 of 12 Photos: Remembering Anzac Day, 100 years on A man places a poppy on the Roll of Honor at the Australian War Memorial in Canberra, Australia. Hide Caption 5 of 12 Photos: Remembering Anzac Day, 100 years on Britain's Prime Minister David Cameron, left, and George Henry Brandis, attorney general for Australia, carry wreaths during a ceremony at the Cenotaph in Whitehall, London, Hide Caption 6 of 12 Photos: Remembering Anzac Day, 100 years on Servicemen and women march wearing period uniforms at the Australian War Memorial in Canberra, Australia. Hide Caption 7 of 12 Photos: Remembering Anzac Day, 100 years on A marching band takes part in the Anzac Day parade along George Street in Sydney, Australia. Hide Caption 8 of 12 Photos: Remembering Anzac Day, 100 years on A poppy is laid on the Tomb of the Unknown Warrior during the Anzac dawn ceremony at Pukeahu National War Memorial Park in Wellington, New Zealand. For the allies, Gallipoli was considered a military failure, though the bravery of Australian and New Zealand troops has long been celebrated. Hide Caption 9 of 12 Photos: Remembering Anzac Day, 100 years on Members of the Albert Battery shoot a volley during the Currumbin RSL dawn service in Currumbin, Australia. Hide Caption 10 of 12 Photos: Remembering Anzac Day, 100 years on People pin poppies to the Cenotaph following the dawn service at the Auckland War Memorial Museum in Auckland, New Zealand. Hide Caption 11 of 12 Photos: Remembering Anzac Day, 100 years on The Anzac torch is lit at the Shrine Of Remembrance at Melbourne Cricket Ground on April 24, in Melbourne, Australia. Hide Caption 12 of 12

"I think it shows that the ideology, if you're open to it, it takes no prisoners ... there are certain people who fall into the seductive propaganda of some of the ISIL stuff that's pumped out on social media.

"He's been caught up in that, he's explored it and he's escalated into an attack plan, and a credible one, which is an extremely dangerous thing to do."

According to authorities, the attack was to have been carried out in person by his co-conspirator, Sevdet Besim, from Melbourne; the pair had set out the details of the deadly outrage in thousands of messages sent using an encrypted app.

But the plan was foiled, police say, when they were called in after the teenager threatened to behead teachers at his school in northern England, prompting counterterrorism experts to crack the encryption code on his smartphone. Besim awaits trial in Australia on charges of conspiring to commit a terrorist act; he has not yet entered a plea.

Alerted by their counterparts in the UK, Australian police closed in and found "the knife, the flag, and the martyrdom ... script," Mole said.

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The boy, who is now 15, was known to have behavioural problems, but his parents, who are divorced, are said to have had no idea their son had been radicalized until police became involved.

The British-born teenager had managed to convince 18-year-old Besim that he was much older and had a history of radicalism, testing the Australian's religious knowledge and determination to carry out an attack.

"He's put himself in the space of authority and Besim has accepted that," said Mole. "That's the mask of social media -- you can, if you [behave] in the right way, ask the right questions, you can show yourself to be that sort of mature person that Besim was ... looking for to give him some guidance."

What is Telegram? Telegram is an instant messaging system which allows users to send encrypted texts, along with photos and videos, via their mobile phone or computer. It was set up by Russian exile Pavel Durov, who says he and his brother Nikolai "wanted a secure means of communication for ourselves." Durov told CNN he believes people have a right to communicate without the government or others being able to see what they are saying. "When law enforcement bodies can get access to the data it leads to abusing that kind of power ... and you can buy any private communication if you have enough money or connections." Durov says he is aware the platform may be used by terrorists, but insists that: "Providing [a] secure private means of communication for ... 99.999% of people that have nothing to do with terrorism means more than the threat we see from the other side."

Authorities claim that over the course of nine days the pair exchanged some 3,000 messages using controversial messaging app Telegram.

Security analysts say members of terror groups like ISIS use encryption apps including Telegram, Surespot, Kik and Wickr to send messages to each other without the risk of them being read by outsiders.

"It is very well known that ISIS -- and not just ISIS -- uses open source social media like Facebook and Twitter to circulate its propaganda," said Charlie Winter, of counter-extremism think tank Quilliam.

"What you also see is people in Syria and Iraq who self-advertise as Islamic State fighters and recruiters and they provide the details to their Surespot account, their Kik account, their Telegram account."

British authorities want the ability to monitor such communications.

"Do we want to allow a means of communication between people which -- even in extremis, with a signed warrant from the Home Secretary personally -- we cannot read?" British Prime Minister David Cameron asked in January this year.

His message has been echoed by Andrew Parker, the head of Britain's security service, MI5, who says counterterrorism forces must be able to monitor suspected extremists.

"MI5 and others need to be able to navigate the internet, to find terrorist communication," Parker told the BBC in early September. "We've been pretty successful in recent years but it is becoming more difficult as technology changes faster and faster.

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"We need to be able to do in the modern age what we have done in our history -- [we] need to be able to monitor the communications of terrorists and spies."

Telegram's co-founder, Pavel Durov, says he is "sorry" that the teenager was using his app to plot the beheading, but insists: "If Telegram did not exist, this young boy would have used some other app."

A Russian exile, Durov says he's seen first-hand what happens when a government has too much power over information.

"What I saw in countries like Russia [and] many other places is that when law enforcement bodies get access or can get access to the data eventually it leads to abusing that kind of power."

He says people have the right to secure communication, and warns it is almost impossible to limit the spread of encrypted technology.

But later this year, the British government plans to introduce draft legislation dealing with encryption -- in the hopes of stopping the next teenage terrorist.