The ringleader of the London Bridge terrorist attack was a teacher at a primary school where he is feared to have radicalised children as young as four, The Mail on Sunday can reveal.

Khuram Butt, 27, taught Koran classes at Eton Community School in Ilford, East London, an independent Islamic school for children aged three to 11. It is suspected that he used the classes to expose pupils to his extremist beliefs.

Just two months before the terror attack, the school was inspected by Ofsted and given a glowing report, which even commended how teachers had fulfilled their obligation to spot and halt extremism in pupils.

Khuram Butt, 27, taught Koran classes at Eton Community School in Ilford, East London, an independent Islamic school for children aged three to 11

This was the very time when Butt was preaching his twisted version of Islam, justifying violence and hatred towards non-believers.

Butt taught in after-school classes as an unpaid volunteer.

The school had previously been known as Ad-Deen Primary School and was exposed by The Mail on Sunday in 2014 as having been set up by an extremist called Sajeel Shahid, 41, who trained the ringleader of the 7/7 attacks at a jihadi camp in Pakistan.

Shahid also set up Ilford's Ummah Fitness Centre – a stone's-throw from Eton – where Butt also worked as a trainer and is feared to have radicalised other young Muslims.

Butt, who lived in nearby Barking, taught at the school in the months leading up to the London Bridge atrocity in June, when he and two accomplices went on an eight-minute rampage, killing eight and injuring dozens.

Butt, Rachid Redouane, 30, and Youssef Zaghba, 22, drove a rented van along London Bridge, mowing down pedestrians, and then jumped out of the vehicle armed with knives and wearing fake suicide vests.

They stabbed as many victims as they could before being shot dead by armed police.

Community sources in East London have told The Mail on Sunday how Butt held Koran classes at the school as a volunteer teacher on most days of the week.

The after-school lessons were attended by most of the school's primary-age pupils, who number up to 30. There are 30 other children at the school of nursery age.

The MoS understands that social services at the local Redbridge Council have now been alerted, as well as the Met Police, who are trying to identify the pupils to see if they have been radicalised.

Community sources in East London have told The Mail on Sunday how Butt held Koran classes at the school (pictured) as a volunteer teacher on most days of the week

The school's proprietor and head teacher is Sophie Rahman, 41, the ex-wife of Shahid. It is believed she has handed to police the names of pupils she fears might have been radicalised by Butt.

After the London Bridge attacks, it quickly emerged that Butt met Redouane and Zaghba at the Ummah Fitness Centre, and CCTV videos of the three terrorists came to light which apparently showed them plotting their murderous attack on the gym's premises. But Butt's work at the school was unknown until now. Bashir Chaudhry, chairman of the Ilford Community Centre, said: 'I heard he used to teach the Koran at the school. He used to teach five pupils at a time.'

Another community figure, who did not want to be named, said Eton School should never have hired Butt as he was known locally as an extremist. In 2016, Butt had featured in the Channel 4 documentary The Jihadis Next Door, about Islamic extremists connected to the banned group Al-Muhajiroun.

The source said: 'This school is known as an Al-Muhajiroun school, because Shahid was from that group and so was Butt. But he should not have been teaching at that school as so many kids could have been groomed by him.'

The school, which charges £2,400 per year per pupil, was inspected by Ofsted in February 2016, and again in September last year. On both occasions, it failed to meet required standards for an independent school.

The inspections said pupils were being taught in 'unsafe' environments, and the school failed to take measures to prevent pupils from going missing from education.

However, in April 2017, two months before the London Bridge attack, Ofsted inspectors said they found the school had improved its standards and fulfilled all its requirements, including 'Prevent duty', which means teachers were trained to spot radicalisation in pupils and act on it.

Armed police (pictured) close in on the London Bridge attackers. Butt, Rachid Redouane, 30, and Youssef Zaghba, 22, drove a rented van along London Bridge, mowing down pedestrians, and then jumped out of the vehicle armed with knives and wearing fake suicide vests

The report said: 'Leaders have undertaken enhanced safeguarding training, including in relation to the 'Prevent' duty… they have trained all the school's staff accordingly.'

But astonishingly, Butt was running the school's Koran lessons at a time that he is now suspected of grooming pupils with extremism.

Although it is not known what level of extremism Butt subjected the pupils to, an idea of his hateful nature was witnessed by a former Muslim who encountered Butt at Speaker's Corner in London's Hyde Park in August last year.

He said Butt threatened him and his friend with murder because they had left their faith.

Aftab, who does not want to give his full name, added: 'He said I ought to be killed because I am an apostate. We became so concerned that my friend started to film Butt with his mobile phone. Neither of us have been to Speaker's Corner since, because we are so scared.'

After the London Bridge attack, Aftab handed over to police the six-minute footage of Butt wearing a Superman vest and preaching extremist Islam.

Last night, Ofsted said in a statement: 'Ofsted does not have the necessary legislative powers to inspect madrassas or after-school centres. We work closely with the Department for Education.

'Eton Community School received a full inspection in February 2016 when it was found to be inadequate. Since then it has had two follow up inspections. In February 2017 we found the school was able to demonstrate it was meeting all the necessary standards.'

The Met said: 'Police are aware of Khuram Butt's connection to the Eton Community School and we are working with local partners to address any safeguarding issues.'

Despite repeated attempts, the MoS was unable to get a response from Eton or Sophie Rahman.

A Department for Education spokesman said: 'It is extremely concerning that an individual like this was allowed to be involved with any school. We will not hesitate to take appropriate action to safeguard children, which can include the closure of schools.'