Ahmed Hassan, 18 (pictured), entered Britain on the back of a lorry

Foster parents of an Iraqi refugee last night demanded to know why he was left free to carry out a Tube bombing.

Ahmed Hassan, 18, entered Britain on the back of a lorry and admitted to Home Office officials that he was trained to kill by Islamic State.

But blunders meant he was placed with the loving couple, who had no idea about his links to the terror group as he secretly built a deadly bomb in their home with a YouTube recipe.

His victims and MPs yesterday questioned why he was let into the UK and why counter-terrorism officials failed to monitor him adequately.

The asylum seeker faces life in jail after being convicted yesterday of trying to kill 93 commuters with a homemade bomb on September 15. He will be sentenced next week.

Hassan plotted under the nose of the Government's anti-extremism programme Prevent, which appears to have failed to act for months despite repeated referrals. Months before the attack, there were signs he was bent on revenge on the UK, yet he slipped the net. Yesterday it emerged:

His foster parents accused the Home Office and social services of putting their lives at risk

Prevent faced questions on why Hassan was referred by charity workers a day after his immigration interview but, it is thought, no contact was made for eight months

Hassan was never referred to MI5 despite being seen donating to IS and declaring it was his 'duty to hate Britain'

He claimed he did not know the attack was wrong as he had Asperger's syndrome, but the Old Bailey judge blocked the defence as he was never formally diagnosed.

Prosecutors said it was 'luck' his device did not fully explode. His target was Earl's Court station, where he hoped to kill hundreds, but the train was delayed and the bomb went off at Parsons Green, injuring 30. Dozens more were wounded as they fled.

Yesterday it emerged that 20 months earlier, Prevent were tipped off about Hassan by charity Barnardo's a day after his first Home Office interview, when he revealed he had been trained to kill by IS.

His college teacher made a second referral in August 2016 after he was seen making a donation to IS. Prevent was called a month later when Hassan disappeared to Wales for a week.

But it was unclear last night what, if any, help he received from the programme.

In a pre-trial hearing, prosecutor Alison Morgan said foster carers Penny and Ron Jones were never told he had been trained to kill by IS.

Hassan tried to kill 93 commuters with a homemade bomb (pictured) on September 15

The couple welcomed Hassan into their home in Sunbury-on-Thames, Surrey, where he stole knives and screwdrivers to build his bomb while they slept.

Mrs Jones said: 'It makes me really angry that anyone's life was put at risk. I feel very betrayed … the Home Office have let everybody down and social services could have found out more information.'

Chris Wildish, who was caught up in the blast, said: 'This country did everything they could to help him … yet he still did this terrible thing.' The case is to be looked at by the home affairs committee.

Penny and Ron Jones (pictured), of Sunbury, who were the foster carers of Ahmed Hassan

Tory MP Sir Christopher Chope, a committee member, said: 'I think it is a legitimate question to ask why did we let him in … our liberal rules are being exploited by our own enemies.'

Met Commander Dean Haydon said Hassan was 'devious and cunning', adding: 'He was appearing to engage with [Prevent], but he kept secret what he was planning.'

Surrey Police and Crime Commissioner David Munro told BBC Radio 4: 'We were too slow, all the organisations involved.'

A Surrey council spokesman said it told Mr and Mrs Jones about Hassan's background 'at the time he was placed'.

Security minister Ben Wallace said police and the council had conducted an internal review. Prevent refused to confirm if and when it spoke to Hassan.

The refugee who hated Britain: How teenager was given everything from a studio flat and a place at college only to repay our generosity with murderous contempt

There was no shortage of clues pointing towards the evil being plotted by Ahmed Hassan in the months after he was smuggled into Britain in the back of a lorry. Weeks after setting foot on UK soil in October 2015, the Iraqi, now 18, told Home Office officials he had been kidnapped by Islamic State and trained to kill.

Then there was the moment a Barnado's charity worker found him looking at pictures of balaclava-clad IS fighters – and the other staff members at a hostel run by the charity who heard him listening to a jihadi song with the lyrics, 'We are coming to you with the slaughter'.

Last but not least, there was the WhatsApp message spotted on Hassan's phone by a teacher at his sixth-form college stating that 'IS has accepted your donation'. He told the same teacher: 'It's my duty to hate Britain.'

It was behaviour that was in stark contrast to the support he received from an army of support workers, mentors, teachers, counsellors and foster carers – all of whom wanted the best for him and went out of their way to help him during the two years following his arrival in the UK.

A single gram of the volatile home-made explosive (pictured) used by the Parsons Green bucket bomber could have killed and maimed

Given Hassan's open hostility towards the country that generously opened its arms to him, the biggest shock of all is that no one was able to prevent him from carrying out his plot on a rush-hour Tube train on September 15 – despite his college tutor referring him to the Government's anti-radicalisation programme, Prevent.

Charity Barnardo's immediately referred the case to Prevent after receiving information about Hassan's immigration interview.

Despite being contacted by Prevent, he managed to fool them into thinking he was co-operating with their efforts and so alarm bells didn't ring among the professionals tasked with looking after him.

It seems no one from the Home Office or social services spoke to Hassan's foster parents Ron and Penny Jones about the teen's IS training or possible ongoing links. The kind-hearted couple were left in the dark about the evil plot being hatched in the upstairs bedroom of their terraced home in Sunbury-on-Thames, Surrey.

Despite Hassan's conviction at the Old Bailey yesterday, there are lingering questions about the real motivation behind his crime.

Was he, as he told immigration officials at Lunar House in Croydon soon after arriving in the UK two years ago, really kidnapped by IS and 'trained to kill' by them, before fleeing the terror group?

Or, as he claimed in court this week, was that simply a fanciful tale he concocted in the hope of gaining asylum here in the UK?

If we are to believe Hassan's latest version of events, delivered under oath from the witness box, he is nothing more than an aspirational middle-class Iraqi who came to the UK in search of a decent education and a better life – and his crime is even more sickening.

As an asylum seeker who entered this country unlawfully, he was provided with a home and an education beyond anything he would have received in war-torn Iraq while his asylum claim was considered.

An injured woman close to Parsons Green station in west London after the explosion on the packed London Underground

Had he applied himself to his studies and embraced the extraordinary opportunities he was offered in the UK, who knows what he might have become?

Those professionals who showered him with support believed he had immense potential.

He was a naturally gifted student at Brooklands College in Weybridge, Surrey, and was named Student of the Year 2017 for his outstanding academic achievements. How ironic that he spent his prize – a £20 Amazon voucher – on ingredients for a bomb packed with nails, drill bits and screwdrivers, aimed at bringing carnage to the very country that had taken him in.

Whatever Hassan's reasons for claiming asylum, there is little doubt life here presented him with opportunities that would have been beyond his wildest dreams in Iraq.

He was born in the capital Baghdad in June 1999 but orphaned at a young age. His mother died before he was old enough to remember her and his taxi driver father was killed in an explosion in 2006. Hassan and his older brother Falah, seven years his senior, were taken in by an uncle in northern Iraq.

Despite excelling at school, by the time he was 15 his education was over and he was working 18-hour days carrying vegetables between lorries on the Iran-Iraq border.

Ahmed Hassan was born in the capital Baghdad in June 1999 but orphaned at a young age

He moved to the IS-controlled town of Jalawla between August and November 2014 – exactly how he spent those four months is not clear. When the town was liberated by the Kurdish Peshmerga, he slipped over the border into Turkey and travelled to Istanbul.

He decided to leave Iraq because he wanted 'a better life', Hassan said in court this week. 'I wanted studying, I wanted to learn English and there was so much pressure on me to keep on with my job.'

After two weeks in Turkey he travelled by ferry to Italy, where he was briefly detained by the authorities and then released, before moving to France.

His last stop there was the Calais 'Jungle' camp where, he admitted in court, asylum seekers shared 'sob' stories for use by others hoping to get to Britain and win the right to stay. 'I have never come across a refugee who would tell the truth when they arrive in a new country,' Hassan told the Old Bailey. 'In fact there were people who used to sell stories.'

The device sits, mangled and only half detonated at the platform at Parsons Green underground station

An London Underground tube carriage stands empty after Hassan's explosive device detonated prematurely

After multiple attempts to get into the UK, he finally arrived in Dover in October 2015 and was taken by lorry to a location near Gatwick Airport.

As a minor, he was swiftly scooped up into care, housed first at Bay Tree, a home run by Barnardo's in Horley, Surrey. One staff member was with Hassan when he was interviewed by immigration officials in January 2016.

He told them that after being 'captured by IS for a few months … I was forced to train with them on how to kill and they would teach us about the religion and what Allah believes is right'. In a later interview, he added that he had been kidnapped and forced to train with IS after the group threatened to kill his uncle and brother.

But while the truth was constantly obfuscated by the endless lies Hassan told, what is clear is the extraordinary level of support he was offered as soon as he arrived.

By April 2016, he had been enrolled on a 'Head Start' scheme at Brooklands College, where he passed GCSE English before embarking on a two-year media course. When Bay Tree hostel closed down, he was moved to a brand new studio flat in a 'semi-independent' unit in nearby Epsom.

Ahmed Hassan (pictured on arrest) was offered an extraordinary level of support when he arrived as a refugee

And when he became 'depressed and unhappy and bored' at the hostel, Brooklands staff arranged with social services for Hassan to move into the home of retired couple Penny and Ron Jones.

While the experienced foster parents showered him with love, his college tutor arranged for him to spend his summer on a Government-funded National Citizen Service programme which involved a week's camping in Devon, a week at Surrey University and a week of charity work in Guildford.

When he expressed an interest in becoming a wildlife photographer 'like David Attenborough', Mr and Mrs Jones took him to Richmond Park and to Monkey World in Dorset. It is hard to see what more could have been done to help the troubled teenager settle into a new life.

All the opportunities he claims he wanted, with the 'better life' he dreamed of while working as a labourer in Iraq, were firmly within his grasp. Behind the scenes, however, there were signs Hassan wasn't prepared to invest in the hard work that would have been required to make something of himself.

While waiting to hear if his asylum claim had been accepted, he complained to teachers and friends about how dull his life was. Attempts by the defence to paint him as depressed and vulnerable do not sit well with the day-to day realities of his situation. Despite being given a generous £90-a-week allowance by his foster parents and an Apple laptop for his studies, Hassan was secretly selling second-hand mobile phones for cash on the internet.

Behind his bedroom door, on which he scrawled 'I'm bored' over and over again, he binge-watched repeats of his favourite Mission Impossible film, mentally substituting himself for Tom Cruise in the action role. 'I had a fantasy in my head,' he said when asked by prosecuting barrister Alison Morgan: 'Why did you do it all?'

In the end it seems a desire for infamy combined with a misguided bitterness towards Britain led Hassan down the wickedest of paths. He told his teacher he blamed the British for the death of his parents. But if so, why did he come to the UK in search of a better life?

Whatever the truth, by July 2017, he was texting his teacher Katie Cable, who also worked as a volunteer mentor for refugees, telling her: 'Your country continues to bomb my people daily.'

During his trial, Hassan consistently tried to play down his motivation for planting the bomb, a device hidden in a bucket concealed inside a Lidl freezer bag. In a bid to mitigate his crime, he claimed the device was designed to 'just burn' not to explode or cause harm.

'It was a fantasy. I was bored. I wanted attention,' he told the court when asked why he had planted the explosive device. 'I just felt it was very attractive to me.'

He added: 'The idea of becoming a fugitive got into my head and it was all I could think about.'

In reality, the only reason the shrapnel-packed bomb didn't cause carnage when it went off in a packed train carriage at Parsons Green Tube station was because Hassan had failed to correctly dry out the chemical ingredients and the device only partially exploded.

In court, his well-groomed appearance was a far cry from the shaggy-haired youth seen in CCTV images just before and after his heinous crime. He no doubt hoped to give the jury the impression he was, as his defence team argued, a young man with a bright future ahead of him. The court heard he still hoped to study media at university in Bristol and has been studying while on remand in jail.

Yet throughout this performance, he consistently failed to make eye contact with anyone in the court. At no point did he appear aware of the magnitude of his crime.

The greatest irony of all is that Hassan could have had the bright future he claims he was looking for. But instead of seizing the opportunities offered to him in the UK, he chose to take the most evil of paths. Exactly why he did it, we may never understand, but he betrayed the kindness, hope and belief invested in him in the most monstrous manner possible.

A spokesman for Surrey County Council said: 'This was a difficult case in tough circumstances. We have a duty to provide support to unaccompanied asylum-seeking children who arrive in Surrey and we're also expected to work with law enforcement agencies and others to help stop people being drawn into terrorism.

'Our work with other agencies in this case wasn't as good as it should have been and we're sorry for our part in that. We knew before the terrible incident at Parsons Green that we needed to make changes and had already begun to do so. Since then we have made further improvements.'