CCTV cameras captured it all. A drug-dealer’s car hurtled down a high street, closely followed by another vehicle. “We need police, please!” a panicked passenger in the first car told a 999 operator. “They’re gonna stab us!” When their car crashed, they dived into a hotel. Nearby, on another day, a man died after he was attacked over an unpaid drugs debt. He was stabbed 15 times.

These ordeals did not play out on London streets, which are in the news following an uptick in murders. Rather, they took place in a Lancashire town called Darwen, which borders pretty moors. Both were directed by drug gangs from Liverpool, 30 miles away. They are extreme examples of the fallout from a shift in Britain’s drugs market, which could be one cause of a nationwide increase in violent crime.

Local dealers once controlled the drugs market in most towns. They would go to a city about once a month to buy drugs from wholesalers. In the early 2000s, London’s kingpins spotted an opportunity to cut out these dealers by recruiting their own couriers to sell crack cocaine and heroin directly to provincial consumers. Coppers call this new business model “county lines”, after the mobile numbers that faraway clients use to place orders. Crime bosses in Liverpool and Manchester began to copy their London peers. The National Crime Agency reckons there are now at least 720 such lines of distribution in England and Wales.

A new report by the Home Office links this shift to big rises in some types of violence. Crime has been falling for years but homicide, gun crime and, in particular, knife crime have gone up since 2014. Although knife offences are still most common in cities, above all London, the biggest rises have been in nearby counties (see map). Data connecting county lines to the surge are sketchy, but it seems to be a “contributory factor”, says Rick Muir of the Police Foundation, a think-tank. The share of murders where the victim or suspect was linked to drugs rose from 50% to 57% in the latest two years for which figures are available. Two-thirds of police forces say county-lines dealers in their area carry knives; others point to related acid attacks. Turf wars fuel violence, as does the need to enforce discipline over couriers.

The model is attractive to kingpins. They might charge a local dealer £700-900 ($1,000-1,275) for an ounce of heroin they bought from an importer for £500. By breaking it up and pushing it to users via their own runners, they could make £2,800. Profitable lines can even be sold or leased to other gangsters. Diversifying into regional markets helps them to avoid competition in cities, and protects their income from busts on home turf. Spells in remote prisons are an opportunity for market research, one police officer reckons.

Take Liverpool, which is second only to London as a county-lines hub. Drugs and gangs are not new there: it had 86 juvenile gangs in 1946 and was known as “smack city” for its heroin problem in the 1980s. But its gangs now also sell drugs in neighbouring counties. Last September 19 people were jailed for conspiring to supply drugs from the city to users in North Wales, as well as those as far away as Cornwall.

Many small towns make promising markets. In Blackpool, a neon sign celebrating “Merrie England” masks a bleaker reality. There are more heroin deaths per person in the seaside town than anywhere else in England and Wales. Two drugs gangs from Liverpool supplied Blackpool in the early 2000s; now up to a dozen are thought to operate there. As competition has risen, gangs have moved on to places like Darwen, which was previously run by local dealers like Kenny Langford, a former manager of the town’s football team who was jailed in 2015. “It’s like ‘Emmerdale Farm’ compared to here,” says a Blackpool resident who has lost two brothers to heroin. “But go there on a Saturday night and it’s got all the same problems.”

Gangs from Liverpool and Manchester are more likely to work together and less prone to turf wars than those from London, says Rebecca Smith of Lancashire Constabulary. This helps explain why drug-related violence in the county is relatively sporadic, police say. Still, tackling gangs is a priority. Darwen’s local council promises “Al Capone tactics” to target dealers’ benefits and housing entitlements.

The Home Office will fund a national co-ordination centre and prioritise stopping teenage recruitment. But its report does not consider whether there is a link between rising violence and fewer coppers on the beat. The number of police officers has fallen by 14% since 2010. Alan Walsh, who runs a boxing club near the base of the Liverpool gang that was jailed last year, says the problem cannot be solved without more neighbourhood patrols, of which he says there are fewer than when he opened the club 14 years ago. “There’s not a massive deterrent there.”