More than £4 million worth of drugs were seized last week as police in London executed a swift crackdown on exploitative 'county lines' gangs.
Around 70 criminal networks supplying crack and heroin from the capital to smaller towns and cities were dismantled in what the Metropolitan Police described as its "best week ever".
As well as uncovering huge wads of cash, stashes of weapons and making 230 arrests, officers also safeguarded hundreds of vulnerable people who'd been exploited and coerced into working for these gangs.
Here, Yahoo News UK explains how county lines drug gangs operate.
County lines gangs explained in nine points
What does "county lines" mean? County lines is a term used to describe drug dealing networks, often run using a single telephone line, or "deal" line. Drugs are transported from cities to rural and suburban areas.
What do county lines drug gangs do? Organised criminals, usually from big cities, manipulate and coerce vulnerable children and adults - often with mental health or addiction problems - to act as 'runners' for them.
Getting these people to transport drugs and cash makes it easier to stay under the police's radar, and so the criminals giving the orders can avoid getting caught themselves.
Some are recruited through "debt bondage", where they are forced to work for the gangs to pay off their debts.
County lines gangs use these runners to supply drugs to rural and suburban areas - known as "going country" - in order to expand their markets and make more money.
There is a lot of evidence to suggest that gang members launder their money through victims' bank accounts.
What drugs do they deal with and transport? County lines gangs primarily sell crack cocaine and heroin. These class A drugs are highly addictive and carry a high profit margin.
Other drugs including cannabis, powdered cocaine and MDMA have been found during raids of gang members' homes, but they are not thought to be their main stream of income, according to the National Crime Agency (NCA).
When did they start? The NCA released its first report on the emerging 'criminal business model' of county lines in a 2015 report, but it is likely the phenomenon existed some time before.
In an interview with crime and justice consultants Crest Advisory, one young person involved in county lines gangs said: "I think county lines have always been there 2017, or even before then…it wasn’t as hot.
"They [police] hadn’t caught on to it. They didn’t have the operations running to do the raids and stuff."
The heroin and crack cocaine epidemics of the 1980s and 90s prompted a significant police response in urban areas, which made it harder to deal in the open, which may have prompted gangs to think of new ways to avoid detection.
How many county lines drug gangs are there? In 2019 the National Crime Agency said more than 3,000 unique “deal lines” had been identified that year, 800 to 1,100 of which were estimated to be active during any given month.
A 2020 Home Office report by Professor Dame Carol Black says the UK's county lines gangs involved 27,000 young people.
According to the Children's Society, 90% of English police forces have seen county lines activity in their area and say the violence is getting worse.
What is cuckooing? Criminals running county lines gangs often set up shop in a rural area or a small town for a short time by taking over a vulnerable person's home.
The term is named after the cuckoo's practice of taking over other birds' nests to raise its own young.
Often victims of cuckooing are drug users, or suffer from mental and physical health problems. Other common targets are female sex workers, single parents and those living in poverty.
Sometimes these people are forced to leave their own homes and find themselves on the streets while gangs use their home as a base of operations.
How are police tackling county lines drug gangs? In 2019, then Home Secretary Priti Patel announced a £20 million package to disrupt county lines gangs.
This included the expansion of the National County Lines Co-ordination Centre - bringing together a multi-agency team of experts from the National Crime Agency (NCA), police officers and regional organised crime units.
British Transport Police teams working exclusively on disrupting county lines gangs have also been set up, as runners often rely on the rail networks to get around.
Home Office funding has also paid for enhanced analysis of automatic number plate recognition to help catch offenders out on the roads.
The government has also been working with money service bureaus to seize dirty money and make arrests for money laundering.
How to tell if a county lines drug gang are in your area. There are a few tell-tale signs that a child in your area could be involved in county lines activity.
According to Crimestoppers, these are the things you should look out for:
Child/young person going missing from school or home, or significant changes in emotional well-being.
A person meeting unfamiliar adults or a change to their behaviour
The use of drugs and alcohol
Unexplained bus or train tickets
Acquiring money or expensive gifts they can’t account for
Lone children from outside of the area
Individuals with multiple mobile phones, tablets or SIM cards.
Use of unusual terms - e.g. "going country".
Unknown or suspicious-looking characters coming and going from a neighbour’s house.
Relationships with controlling or older individuals, or associations with gangs.
Suspicion of self-harm, physical assault, malnutrition or unexplained injuries.
What to do if there's a county lines gang near you. In an emergency, or if you see a crime being carried out, always call the police on 999.
If you have any information about somebody who has recently moved to set up an illegal drugs network and who may be using violence or abuse to carry out their activities, you should contact Crimestoppers.
You can call its contact centre on 0800 555 111 anonymously or use its non-traceable online form.
Crimestoppers will never ask for your name, and your phone call or online report will never be traced.