By ITV News Correspondent Dan Rivers and Foreign News Editor Jonathan Wald
For the last six months, ITV News has been investigating this underworld, seeking to understand the challenges faced by those who are in Britain without paperwork.
Our inquiries in Calais suggested there may have been some sort of people smuggling route operating between Liverpool and Canada.
It seemed extraordinary so we started making inquiries in the UK.
Our undercover reporter posed as an undocumented migrant and was repeatedly told there was a man originally from Iran who may be able to help with this route.
Canada is a destination many undocumented migrants feel is a promised land, where gaining asylum is perceived as much easier.
Charities that work in this sector say the so called "hostile environment" for migrants in Britain has made it incredibly difficult to successfully obtain asylum.
Little wonder some think getting to countries like Canada is worth the effort and money.
It took several days for our reporter to gain the trust of those with the contacts to finally get a mobile number for this Iranian man, who we now know is called Reza Pour.
Dan Rivers on why undocumented migrants are prepared to risk the black market
During the initial conversation, our reporter asked about getting to Canada and Pour, a 47-year-old originally from Tehran, said while he thought people had managed that in the past, he couldn’t help with that now, but he could help obtain a US passport for him.
"I have entrusted this to someone to see what I can do for you," Pour told our reporter.
Finally a meeting was set up in Liverpool.
Pour’s associate, who he mentioned on the phone was a man called Wahid Fakhrlou.
He was the first to arrive.
Pour arrived shortly afterwards, settling in for a tea at a busy cafe in a shopping centre in Liverpool.
Despite the public setting, Pour, Fakhrlou and our reporter immediately got down to discussing how to illegally obtain a passport.
Not a British passport; these men were offering to get a US passport for our reporter to travel via Ireland, eastern Europe, south America and into Canada.
They claimed the passport would be genuine but they would "obtain" one whose real owner had a likeness to our reporter, hoping that airport officials would fail to notice the discrepancy between the bearer and the photo.
It’s not clear whether the passport would be stolen to order or whether the real owner would be bribed to give it away.
Either way, it was clear this would be facilitating illegal travel to north America.
Pour acknowledged this would be illegal.
Fakhrlou confirmed the price would be between £8,000 and £12,000 for the passport and £4,000 for the travel, payable in advance to Pour.
Fakhrlou also claimed the plan had worked successfully in the past.
What is even more eye-raising, is that Pour worked as an official translator on a freelance basis for a number of government organisations including Merseyside police, Greater Manchester Police and also worked for the court service via a firm subcontracted to provide interpreters. He also told us off camera that he works for the Home Office.
His associate Fakhrlou claims he is an undocumented migrant from Azerbaijan who has been here for at least 8 years.
His associate Fakhrlou, claims he is an undocumented migrant from Azerbaijan who has been here for at least eight years.
Of course, our reporter declined to go through with the plan, but we managed to track down Pour afterwards and confronted him.
You can see his response here, but essentially he claimed the whole episode was a misunderstanding, denied he was involved in people smuggling or anything unlawful and he was simply trying to help a desperate person.
Fakhrlou sent us a WhatsApp message responding to our questions saying: "I became greedy and thought I can abuse the opportunity that I faced but I am not a greedy person and changed my mind."
It’s true that being in this country without documentation does make many people desperate, even if their grounds for claiming asylum are genuine.
Asylum seekers cannot work legally while their application is processed.
Often they have no choice but to stay in poor accommodation for months living on approximately £5 a day while their claim for asylum is processed.
Charities have said since the Immigration Act 2014 employer checks mean much more severe punishments for those who pay undocumented migrants for work.
It forces many into the black market to make ends meet and leaves many looking for a way out.
One NGO worker told me the entire asylum system seems designed to "catch people out".
Minor administrative errors can invalidate an application entirely.
The whole sector is also riddled with substandard legal advice, by unqualified people who are more interested in making money rather than helping those in need.
And then there are people like Pour and Fakhrlou who offer to obtain a passport for huge sums of money, tempting undocumented migrants into breaking the law to travel abroad.
Charities say it’s common for them to see asylum seekers who have had enough and want to leave the UK.
They speak of a lack of flexibility and discretion in a system which is labyrinthine in its complexity.
Most don’t have the money to pay for a passport, but instead resign themselves to travelling back to the unstable countries they have left.
This is known as "voluntary return" but they claim there is now no longer government funding for charities to offer independent impartial advice on voluntary return.
It’s not known how many undocumented migrants there are in this country, but as we have seen in Essex last week, many risk their lives to get here in the hands of people smugglers and traffickers.
Once they are here though, many discover the streets are not paved with gold.
They are often forced to work long hours, for little money to repay a so-called debt to the smuggling gangs.
Often they are working in plain sight - in illegal car washes, in dodgy nail bars or massage parlours.
They find themselves trapped, unable to go home even if they wanted to, but unable to lead normal lives here either.
Little wonder some are willing to exploit them or rip off with the promise of a new dream in a different country.