THE 'kingpin' behind a large-scale drugs operation in Oxford is facing a lengthy jail term.

Marlon Thompson, of Earlon House, Islington, London, had already admitted two counts of conspiracy to possession of class A drugs, cocaine and heroin, with intent to supply.

But Oxford Crown Court heard at a hearing yesterday that the 22-year old was the 'ringleader' behind the scheme to flood the city with drugs from his London base of operations.

Prosecutors said he was known as 'Gucci' in reference to the name of the drugs line in which he sold heroin and cocaine to addicts across the city.

Addressing Thompson, prosecutor Jonathan Stone told the court: "The fact is that when people phoned up that Gucci line they spoke to you.

"You are the Gucci line, you are Gucci. You are the main man.

"You decided to set up stock in Oxford because there was less competition than there was in London."

The scale of the drug dealing first came to light, the court heard, after two undercover officers, codenamed Joe and Rich, busted the illicit operation after covertly recording a number of drug deals.

Of these, Thompson was implicated in at least seven separate deals, the court heard yesterday, and taking to the witness box he admitted that he was sometimes in Oxford to ply drugs as often as five or six days a week.

Another man, who is also set to be sentenced for his part in conspiracy to supply drugs, Khair Oram, of Glen Parva, Wigston, Leicestershire, told one undercover officer in another recorded deal that he was 'Gucci's little brother' in a reference to Thompson being the boss.

When he was ultimately arrested by police, Thompson was found to have on him a Samsung mobile phone - which prosecutors said was used as part of the Gucci line after analysis, as well as 20 wraps of heroin.

Mr Stone said yesterday that Thompson was also insured on a number of cars used in the drug deals including a BMW 64-plate registered in 2014, factors which suggested he had a 'leading role' in the enterprise.

He also revealed Thompson had been sentenced for earlier drug offences in 2012.

He added: "The fact is that it is four years later and you are no longer a runner, you have moved up the chain. You are now running your own drugs line."

Thompson's defence team, Lucy Tapper, meanwhile argued during yesterday's hearing that despite his guilty plea, her client was not the 'criminal kingpin' prosecutors alleged and had acted 'under pressure' to deal the drugs for those higher up in the chain after incurring a debt of some £3,400.

Deciding the issue of his role in the drug dealing Judge Andrew Goymer dismissed this argument, saying he was at the top end and played a 'significant role' in the dealing.

He said: "I am satisfied that this defendant did have a substantial degree of control of the Gucci line.

"The evidence suggests and shows the operational and management function he is clearly handed, with what is clearly a good deal of awareness of the scale of the operation."

Thompson's appearance at court follows one of Thames Valley Police's biggest ever raids and a crackdown on criminal gangs supplying drugs codenamed Operation Spires.

More than 180 police officers raided 24 properties across Oxfordshire in January last year, including 10 homes in Oxford, two in Abingdon and 11 in London.

A total of 22 people were arrested as part of the year-long investigation into heroin and crack cocaine supply.

Thompson will be sentenced for his role in the drug dealing enterprise at the same court on Monday.