British plumber Adam Locksley was being questioned by anti-terror squad detectives last night

A suspected fundraiser for barbaric terror group Islamic State was dramatically arrested yesterday following a Mail on Sunday investigation into a sinister network operating in Britain.

British plumber Adam Locksley was being questioned by anti-terror squad detectives last night as officers from Scotland Yard’s SO15 unit searched the 28-year-old’s North London home.

The arrest came after this newspaper handed police evidence from a three-week undercover operation that reveals how notorious British fanatic Omar Hussain, known as the Supermarket Jihadi, organises cash collections from IS sympathisers in the UK from his hideout in Syria.

Our expose also reveals how:

Young supporters of the terror group are told to steal from non-Muslims to raise cash for jihadis;

Money is being funnelled to Syria via Western Union and Moneygram cash transfer systems to buy weapons, clothes and equipment for IS fighters;

The terrorists even arrange couriers to collect money from donors in person, but use elaborate plots to avoid detection;

The network communicates via a highly-encrypted messaging app called Kik, under the noses of police and security services.

The fundraising cell was infiltrated after a reporter posed as a would-be donor offering to give money to jihadis in Syria.

The reporter contacted Hussain in Syria on Kik and was immediately encouraged to donate money.

A series of exchanges then took place between the reporter and associates of Hussain in Syria and Britain, and a cash drop was arranged. The dramatic sting unfolded when an IS middleman then sent Locksley to pick up £1,000 cash hidden in a package among bags of sand outside a builders’ warehouse in North London.

The reporter did not leave any money inside the package as this would have been against the law.

The package merely contained an A-Z map book of London.

During the carefully planned operation, which involved expert security staff, Locksley picked up the package while appearing to receive instructions on a mobile phone, and was secretly photographed.

It is not known whether Locksley knew there was ‘money’ inside the package, which was allegedly intended to be sent to IS to buy weapons in Syria.

The dramatic sting unfolded when an IS middleman then sent Locksley to pick up £1,000 cash hidden in a package among bags of sand outside a builders’ warehouse in North London

We later handed our evidence to police who, within 12 hours, arrested Locksley. Last night, a Metropolitan Police spokesman said: ‘Detectives from the Counter Terrorism Command [SO15] have arrested a man on suspicion of terrorist fundraising.

‘The 28-year-old man was arrested on Saturday afternoon, October 24, near to his home address in North London on suspicion of terrorist fundraising, contrary to Section 15 of the Terrorism Act 2000. The arrest was made under the Police and Criminal Evidence Act and he was taken into custody at a North London police station where he remains at this time. A search of his address is ongoing.’

Shortly after Locksley’s arrest, four detectives arrived at his flat in Hendon to search the property. After four hours the officers led away two women wearing headscarves from the property. Neighbours said Locksley was a polite and quiet man, who lived with a young Middle Eastern-looking woman, believed to be his wife.

The reporter did not leave any money inside the package as this would have been against the law. Pictured is Adam Locksley arriving to pick up the package

Locksley’s landlord and neighbours said he was a white British convert to Islam. It was not clear when he adopted the religion.

He was said to have an English father and an Irish mother, and to speak with a London accent. Another neighbour said that recently she had nearly called the police as she became suspicious of people going in and out of the flat.

The neighbour, who did not want to be named, said: ‘I always hear people coming and going at all hours.’

Our investigation began after our reporter obtained a Kik address for the Supermarket Jihadi through a blog page he ran on the blogging site, Tumblr.

Hussain is infamous for giving out advice to would-be jihadis on how to get to Syria from Europe without getting caught.

The page has since been taken down by Tumblr.

During the carefully planned operation, which involved expert security staff, Locksley picked up the package while appearing to receive instructions on a mobile phone, and was secretly photographed

It is not known whether Locksley knew there was ‘money’ inside the package, which was allegedly intended to be sent to IS to buy weapons in Syria

After the reporter contacted Hussain on Kik, Hussain sent a long group message saying how IS was desperate for money. He wrote: ‘To those who love the Islamic State and wish to assist in its expansion, we are in dire need of financial support for the sake of Allah. Alhamdulillah [praise be to God] we are currently working on a few projects for which we require financial aid.’

In the same message, Hussain gave the name and Kik address of an American jihadi in IS-controlled Syria, called Abu Issa Amriki, as the person to contact if anyone wanted to donate money.

When the reporter contacted Amriki on Kik, he was asked to donate as soon as he could. Amriki encouraged the reporter to donate as much as 1,000 dollars or euros.

Amriki told him that he could raise the money through charity or by ‘stealing’ from non-Muslims. Amriki said: ‘Stealing from kuffar [non-believers] for mujahideen [jihad fighters] is halal [lawful].’

When asked what the money was going to be used for, Amriki replied: ‘Medicine, drones, night vision, thermals, range finders, sniper scopes, weapons, clothes for brothers, daily expenses for mujahideen… any families of the shaheed [dead jihadis].’ He asked the reporter to send the money by Moneygram transfer to an IS agent in Bosnia.

Locksley’s landlord and neighbours said he was a white British convert to Islam. It was not clear when he adopted the religion

But the reporter refused, saying that there were too many CCTV cameras inside Moneygram shops and he feared being identified.

A few days later, Amriki contacted the reporter again by Kik, saying he had a British-based IS fundraiser who could come to collect the money from him.

Amriki wrote: ‘Akhi [my brother] i might have a brother close by to u, a british brother who can pick up the money from you. R u interested to give?’

When the reporter told the jihadi that he would be willing to meet the UK-based agent, Amriki sent the investigator the Kik address of the British IS sympathiser.

The UK-based IS agent called himself Abu Abdul-Rahman Britani.

He said he needed ‘to stay under the radar’.

But Britani did reveal that he was collecting money for IS throughout the UK using a network of couriers.

He also said that he did not live in London, and had tried to enter Syria twice before through Turkey, but failed after he was caught by Turkish security forces.

Britani too asked the reporter if he could send money to him by Moneygram, or deposit the cash into a British bank account. The reporter refused.

Britani then agreed to send a pick-up man to meet the fake donor, but tested him first by asking him questions to make sure he was not a police officer or MI5 agent.

The reporter, who said he lived in Acton, West London, was asked which mosque he prayed at.

He was also asked theological questions about the Koran.

After the questions and answers, Britani said he was ‘happy’ the reporter was a genuine Muslim.

After the reporter contacted Hussain on Kik, Hussain sent a long group message saying how IS was desperate for money. Pictured is the van leaving Selco Warehouse in Cricklewood

He then arranged to send his ‘pick-up brother’, but warned: ‘Don’t forget akhi [my brother] this brother is picking up charity money.

‘He does not have any ties to me or dawla [IS] so don’t talk to him about anything like jihad or anything like that.’ As our investigation continued, early last week the reporter contacted Britani and asked him to send details of a bank account to deposit the money into instead.

Britani provided the sort code and account number of a Barclays Bank account, which he said belonged to a business called AWG Plumbing and Heating.

He told the reporter to deposit the money into the account, and reassured him not to be scared as it was a ‘legitimate’ business.

We discovered that AWG Plumbing and Heating was based in Hendon, North London, and appeared in directories such as Yell.com.

When a second MoS reporter posing as a customer called AWG, a man answered the phone and identified himself as Adam Locksley.

He also gave the fake customer his Gas Safe Register number. The certificate revealed his name and age, home address in Hendon, and a photograph of his face.

THE SET UP: HOW OUR MAN TRICKED 'SUPERMARKET JIHADI' VIA TEXT INTO EXPOSING NETWORK OF ISIS MONEYMEN IN THE UK Advertisement

Inquiries made around Locksley’s flat in Hendon revealed that he drove a silver Nissan van with an Irish number plate on it. Meanwhile, the first undercover reporter messaged Britani on Thursday – the day he was supposed to deposit the £1,000 in AWG’s account – that he could not do it, as there were too many CCTV cameras inside the Barclays branch.

He asked Britani to revert to the original plan. He agreed, and on Friday morning Britani messaged the reporter saying the money could be collected by midday.

Britani told the reporter to go to a branch of builders’ merchant Selco in Cricklewood Broadway, North London. Britani told him that he would meet a courier called Omar, a slim, white Muslim, about 5ft 10ins, and with a ‘handful’-sized beard.

Security advisers warned the MoS team that it was too dangerous to meet for fear of kidnap or violence. Instead, we agreed that we would leave the package at the location for the courier to pick up.

The arrest came after this newspaper handed police evidence from a three-week undercover operation that reveals how notorious British fanatic Omar Hussain, pictured, known as the Supermarket Jihadi, organises cash collections from IS sympathisers in the UK from his hideout in Syria

Just before 12pm, the reporter left an A4-sized brown envelope with ‘To Omar’ written in bold handwriting on the envelope on top of a large yellow sandbag and messaged Britani.

He said: ‘I have just put the brown envelope with “To Omar” written on it on a sandbag by the gate.’ Within minutes, the pick-up man, entered the parking area of Selco, picked up the package and went to his van.

Photos of the man taken by our photographers at the scene matched those of Locksley on his Gas Safe Register.

The number plate on the man’s van matched that of the Transit van we saw outside Locksley’s flat.

Shortly after Locksley picked up the package, Britani sent a series of Kik messages to the reporter.

He said: ‘A-Z book of London. You think your [sic] funny.

‘You wasted the good brother’s time and our time. We wanted to help you give charity to the poor but you’re a game player.’

He added: ‘Are you even a Muslim? Who are you really?’