In 1999, back when Blockbuster was booming and the world was collectively freaking out about Y2K, a crack and heroin-selling crew called "The Londoners" started muscling-in on Brighton's lucrative street drug market. In doing so, they were to change the British drug trade forever.

This crew was different from the other street sellers in Brighton, mainly a mix of well-integrated, home-owning Liverpool gangs and a ragtag collection of local heroin user-dealers, some of whom sold the Big Issue. The new boys of the seaside city, however, were young black guys who commuted from Brixton to Brighton and back each day. Operating under a single phone number and managed by elders back home, they had begun taking over heroin users' council flats to utilise as drug selling bases.

Armed with mobile phones, they sold by appointment only to groups of drug users in Brighton's city centre. Their wraps were high purity and their sales technique was strictly business: no real names, no IOUs and no pointless chit-chat.

Despite regular claims that the drug enterprise model now known as "county lines" – where city drug gangs send teenagers away to sell product in smaller towns – is a brand new type of crime that’s gone largely unreported, this tactic was already a well-oiled machine operating in Brighton at the beginning of the millennium. Its expansion since then has left a trail of destruction across the UK, including the mass exploitation of highly vulnerable young people and addicted drug users, increased violence and the proliferation of 24/7 drug markets providing cheaper, higher purity crack and heroin.

Which leads to the question: why was such a pernicious trend ignored at a national level for so long?

Photo: Lev Dolgachov / Alamy Stock Photo

Pete, now a care worker in his late thirties, was addicted to heroin and crack in Brighton, and was a daily street buyer between 2001 to 2008. "I was buying crack and heroin from 15 and 16-year-old south London boys on BMXs on the strip in 2001," says Pete. "It was well-established by then. I was only 20 at the time, but even I had pangs of guilt about buying off them. I thought, 'Fuck, you’re young.'

"We used to call them the 'away day boys'. They were all working shifts. They would come down on the train from Croydon and Brixton, get off at Preston Park and set up flats with heroin users. They were industrious and uber-reliable. Most of the other dealers in Brighton were a bit of a shambles; most of them stopped selling by 9PM or had their phones turned off. But this lot were 24/7 – you could buy at 4AM, no problem."

Pete knew the names of the dealers who were supplied from Liverpool, and even their partners' names and where they lived. But the London crews operated "like a faceless machine".

"I never knew their real names – they had funny street names, like 'Ice' and 'Ninja'. They were young black kids and all their customers were white. They despised us. They used to spit the drugs out on the floor and laugh at us crawling around for them," says Pete. "But they did three bags for £50 and it was better quality than the Brighton lot."

Brighton wasn't the only destination for England's original county lines gangs. By the second half of the 2000s, drug sellers commuting from London were well-known fixtures on the streets of other southern coastal towns, such as Bournemouth, Worthing and Ipswich. The spread of young city boys selling hard drugs out of town was reflected in the music at the time, by artists such as Joe Black, who spent time in jail for dealing heroin and crack in Reading, and who was openly rapping about "going cunch" in 2008.

It wasn't just heroin and crack these gangs imported into the countryside, but also violence and gang culture: the expansion of drugs into rural and coastal areas was signposted by a rise in supplanted urban violence. It was no coincidence, for example, that the rise of London gangs selling in Southend led to a steep rise in stabbings and shootings

In 2007, a year after 24-year-old south Londoner Jimoh Plunkett was killed after being caught in the crossfire in a shoot-out between rival London gangs at Ipswich's Zest nightclub, police acknowledged they were struggling to cope with waves of young dealers commuting from London to sell crack and heroin in the Suffolk town. As soon as one crew was arrested, fresh faces would arrive in their place, selling from the same SIM card.

The more that gangs expanded into the countryside, the younger the crews seemed to get. In a 2008 article in the Ipswich Star headlined "Army of teens dealing crack and heroin", Detective Chief Inspector Mark Jepson warned that over a third of Class A drug dealers arrested in Ipswich were under 21, with some as young as 15, and the majority were from London. One of the young Londoners dragged into the county lines game in Ipswich was Kirsha Dyer, the sister of former professional footballer Kieron Dyer, jailed for almost five years for conspiracy to sell heroin and crack.

DCI Jepson was one of the first senior officers to openly warn that some of the dealers being sent to work out of London may not simply be in the game to get rich quick, but were instead being exploited. "You could almost class some of these youngsters as victims," he said at the time. "They may have incurred drug debts… and the only way to pay that debt off is to bring drugs into the town. A number will plead guilty at the first opportunity because it gets them out of the system. Otherwise, they could suffer further problems if they return, because not only are they still in debt, but they don't have the drugs or money."

He could not have been more accurate. While police forces around the UK issued public warnings to city dealers to stay off their patch, and devoted a huge amount resources to tackling the expanding numbers of dealers sent out of town, no one seemed willing or able to join the dots. It would be several years before the reality behind going country – its rapidly rising pervasiveness and the fact so many exploited people were being locked up instead of helped – would be accepted.

Photo: Aleksei Gorodenkov / Alamy Stock Photo

In 2015, a groundbreaking piece of research into the links between gang involvement and young people going missing, and an intelligence report published by the National Crime Agency, shifted what was now being called "county lines" into public awareness. Now, after heavy coverage in the media, county lines is being investigated by MPs, is the subject of Home Office guidance and the focus of a new anti-violence strategy.

But all this has come too late for many. When the Londoners were taken out by Brighton police in 2000, only to be swiftly replaced by another crew from the capital, two of them turned out to be school-age kids: a 16-year-old caught with £6,000 cash who was given 12 months probation for dealing heroin and crack, and 15-year old called Tunde Allimi, also charged with dealing heroin and crack. Allimi was unable to appear in court because he had died two months before his trial, killed back home while riding pillion on a motorbike, being chased by police who wrongly thought it was stolen. Meanwhile, the unfortunate heroin user whose house they had "cuckooed" – taken over to sell from – was given an eight-year jail sentence for his troubles.

Victor Marshall, now a retired DSI working at the Police Superintendent’s Association, was head of Brighton’s Drugs and Crime Unit when the Londoners were taken out. He told me that what he was tackling 18 years ago was no different to what people now call county lines.

So why does he think it took so long for the government and national police agencies to get to grips with it? Marshall says county lines were perhaps allowed to flourish undetected at a national level for so long because when the regional crime squads made way for the Serious Organised Crime Agency (the predecessor to the NCA, which ran from 2006 to 2013), local forces became less able to share their problems and get assistance. SOCA's remit was more angled at international crime, and so issues like county lines fell into a policing "void".

Alan Caton, a retired superintendent and current chair of Islington Safeguarding Children Board, was Ipswich's police commander in the mid-2000s. He agrees that a lack of police co-ordination at a national level meant police and the government were "slow off the mark" in dealing with county lines. "We were all dealing with it in isolation, we just dealt with what we were confronted with – we had no idea of the bigger national picture," he says. "Could it have been dealt with sooner? Yes, it could have – and should have – been done sooner, but it wasn't."

But this wasn’t the only reason county lines was left to thrive unchecked for almost two decades. The possibility that young heroin and crack dealers, or people whose homes were used as drug dens, could actually be victims does not fit into the accepted black-and-white narrative which says everyone involved in the drug trade is a total scumbag. This is why it took so long for the authorities, blinded by a moral crusade, to get their heads around the issue.

Crime experts I have spoken to say county lines was only able to be taken seriously at a national level because of the shift in government and police priorities, towards issues such as child sexual exploitation, child trafficking and vulnerability, rather than simply enforcement. But like grooming, the issue of county lines was ignored for too long – maybe because it was an issue where the victims came from some of the poorest neighbourhoods in the UK.