Mr Aylett describes the drug-dealing world as "one of turf-wars, rivalries and pathetic claims for respect".

He adds: "When drug-dealers fall out, they do not take their problems to the police. Instead, they take matters into their own hands, prepared to use serious violence in order to prove whatever point it is that they wish to make.

"The prosecution allege that all four defendants had gone together in Petrovic’s car to Harold Hill in order to mete out violence – and not, as Petrovic has claimed, to collect money and drugs.

Mr Aylett says it is the prosecution's case that the four males "acted together as part of a joint plan to cause at least really serious bodily harm to someone in that park, even if Jodie Chesney was not necessarily their intended target."

"If the prosecution are right in saying that Jodie Chesney was an entirely blameless individual who got caught up in some quarrel between drug dealers, then her murder was the terrible but predictable consequence of an all-too casual approach to the carrying – and using – of knives."

Roughly two hours after Jodie had been murdered, police officers were called to a "bizarre and apparently unconnected incident" in nearby Gidea Park, Mr Aylett has said.

"About two miles from Romford," he adds. "A black Vauxhall Corsa had been abandoned by its owner. Albeit in very different circumstances, the car had been blocking the road. The car had an ‘07’ (and not an ‘08’) registration.

"The car was registered to the first defendant, Manuel Petrovic."

Mr Aylett told jurors the car had been picked up by an Automatic Number Plate Recognition (ANPR) system just nine minutes before the murder of Jodie in Harold Hill.

Jurors have been told the four defendants were "involved in the supply of drugs".

Mr Aylett adds: "As it happens, in the past, one or more of Jodie’s friends had bought cannabis from one or more of the defendants.

"There is, however, nothing to suggest that Jodie was involved in the supply of drugs or that she might have upset anyone. Indeed, the evidence of her character, accomplishments and popularity are entirely to the contrary.

"Jodie’s father Peter has described her as 'a beautiful, well-liked, fun, young woman who judged no-one and loved everyone'.

"So, the prosecution suggest that Jodie is unlikely to have been the intended target; more likely is that the intended target was somebody else altogether."

Image source, PA

Prosecutor Crispin Aylett has described the attack on Jodie as a "terrible and cowardly".

He adds: "Indeed, the attack was so unexpected and so sudden that a number of Jodie's friends had not even noticed the two males.

"None of the local residents had seen anything. Several of the nearby houses did have their own CCTV cameras but any film recovered by the police was of poor quality.

"The murder of Jodie Chesney very quickly attracted publicity at a national level. But, for all the expressions of sympathy and dismay, no one had any idea as to who could have been responsible for this shocking crime."

A local resident heard the sound of screaming, jurors have just been told.

Mr Aylett adds: "She came out to help and placed Jodie in the recovery position and tried to comfort her. As might be imagined, Jodie's friends were hysterical."

Emergency services arrived shortly after, but Mr Aylett said Jodie was "showing no signs of life".

"A team of doctors were dispatched to meet an ambulance half-way," Mr Aylett adds.

"The rendezvous took place at an Esso Garage in Gants Hill. There the doctors performed emergency surgery in an attempt to get Jodie's heart beating again.

"About an hour after she had been stabbed, the poor girl was pronounced dead on the forecourt of the petrol station."

The court has heard that Eddie Coyle saw a "taller male swing his right arm in the direction of Jodie's back".

"Jodie screamed," says Mr Aylett.

"The two males ran off, noiselessly disappearing into the darkness from which they had come.

"Jodie collapsed to the ground.

"Using a mobile phone as a torch, one of her friends could see that Jodie has sustained a deep stab wound to her back and she was bleeding heavily."

Image source, PA

Prosecutor Crispin Aylett QC has began the case by saying Jodie was with "half-a-dozen friends" at the park in Harold Hill on 1 March.

He adds: "They had gone there to chat, listen to music and to smoke cannabis. This was something the group of friends often did together.

"By around 21:20 GMT it had been dark for some time. It was then that Jodie's boyfriend, Eddie Coyle, noticed two figures coming out of the darkness towards them.

"Jodie was sitting on a bench table with her back to the two males coming towards her.

"They made no noise and Jodie would neither have seen nor heard them approaching her."

Danny Shaw
BBC Home Affairs Correspondent

Trials that are likely to last a long time sometimes begin with two 'alternate' or 'substitute' jurors sitting alongside the 12 who have been selected.

This is in case one or two of the 12 have to pull out early.

If this happens, the substitute jurors can slot in without the trial having to start all over again, saving time and money.

In the past, there have been trials which have had to be re-started because one or two of the 12 jurors found they could not continue.

If, after several days or a week, the substitute jurors aren't needed then they'll be allowed to leave the trial.

Manuel Petrovic, Svenson Ong-a-Kwie and the two teenage boys have all stood up in the dock as they hear the 14 jurors take the oath or affirmation to try the defendants on the evidence presented before them in the trial.

The family of Jodie Chesney has arrived at the Old Bailey as the trial into her death begins.

Courtroom eight is full of members of the press, barristers, Jodie's family and people in the public gallery.

Judge Wendy Joseph QC has started to address the panel of 12 jurors who were selected yesterday and another six who are being used as "spares".

Danny Shaw
BBC Home Affairs Correspondent

After all the prosecution evidence has been heard, the defence is allowed to call its own witnesses, including the defendant.

The exercise takes place in reverse, with the defence barrister asking questions first.

When all the evidence has been completed, the jury hears closing speeches from prosecution and defence barristers where they put forward their final arguments.

Then the judge summarises the evidence during the trial and issues instructions to the jury about the law.

After that, the jury retires to consider its verdict, which, at least initially, must be unanimous - all 12 jurors agreed.

If there is a guilty verdict, sentencing may take place straight away, or it may be postponed to allow the judge to consider reports from the probation service and other experts.

Danny Shaw
BBC Home Affairs Correspondent

Before a criminal trial starts, there are usually weeks, and often months, of preparation, including court hearings to deal with administrative and legal points.

The trial itself starts with an introduction by the judge to the jury to set out key legal and procedural issues.

Then the prosecution barrister outlines the case from the Crown's point of view. This can take a couple of hours or a couple of days, depending on how complex the case is and how much evidence there is expected to be.

After that, the prosecution calls witnesses.

Each witness gives evidence 'in chief' where they're asked questions by the prosecution barrister. Then, the barrister for each defendant has the opportunity to question the witness - cross-examination - before further questions from the prosecution barrister.

The judge may also intervene to ask questions.

There may also be occasions when the prosecution barrister reads out statements from witnesses or experts that have been agreed with the defence and are not contested.

Image source, Met Police

Jodie has been described by her family as "a kind and giving person" - and someone who "will obviously be greatly missed".

She attended Havering Sixth Form College studying psychology, sociology and photography and was also an active scout member and volunteer.

The 17-year-old achieved her Duke of Edinburgh Bronze and Silver Awards.

Her family say Jodie loved music and would frequently sit and play the piano in the family home.

Classical composers like Ludovico Einaudi and Beethoven were among her favourite.

Image source, PA Media

Danny Shaw
BBC Home Affairs Correspondent

A Section 45 order is a legal ruling made by a judge which bans publication of the identity of any witness, victim or defendant aged under 18 who appears at a magistrates' court or a crown court.

The ban includes reporting the young person's name, address, school, college or place of work - and any details that are likely to identify the person. Photographs of the individual are banned as well.

The rule relates to all reports of the case on radio, television, newspapers, magazines, online and social media.

The ban applies during the duration of the trial and all other related criminal proceedings, and until the person turns 18.

Witnesses and victims may apply for lifelong anonymity, so they cannot be named even after they have turned 18.

A judge may decide to lift the restrictions on a young person who has been convicted, but this only happens in exceptional circumstances.

It is a crime to breach a Section 45 order and can result in a prison sentence.

Image source, Julia Quenzler

In total there are four males who are all charged with the murder of Jodie Chesney - aged between 16 and 20.

They are:

• Manuel Petrovic, 20, of Romford (pictured)
• Svenson Ong-a-Kwie, 20, of Romford
• A 16-year-old boy - who cannot be named for legal reasons
• A 17-year-old boy - who also cannot be named for legal reasons

Image source, PA

On the night of Friday 1 March, Jodie Chesney was with her boyfriend and friends socialising and listening to music at a children's play park in the Harold Hill area of Romford in east London.

Shortly after 21:30 Jodie's group of friends were approached by two men and one of them stabbed the 17-year-old in the back.

Despite the best efforts of the emergency services, Jodie was pronounced dead a short while later.

A murder investigation was subsequently launched by the Metropolitan Police.

Image source, PA

Two teenage boys and two men stand trial accused of murdering 17-year-old girl Jodie Chesney who was stabbed to death in east London earlier this year.

We will be at the Central Criminal Court - otherwise known as the Old Bailey - bringing you live updates throughout the trial.

The case is expected to open later this morning where the prosecution will outline its arguments against the four males accused of killing Jodie.

On Monday morning, when a jury panel was selected, every bollard and sign outside the famous court was decorated with a purple ribbon - Jodie's favourite colour.