Party goers at an event where a teenager was allegedly murdered on the dancefloor have recalled seeing the 17-year-old laid down and covered in blood.

Charlie Cosser was fatally stabbed in the chest at the outdoor event called “BalFest” – attended by around 100 people at a farmhouse in Warnham near Horsham on July 23 last year.

A teenager, who was 16 at the time, is on trial accused of Charlie’s murder.

The Argus: Charlie Cosser died in hospital last July 25Charlie Cosser died in hospital last July 25

The prosecution allege the fatal injuries took place when a fight broke out between him, Charlie, and two other boys on the dance floor after the defendant and his friends were asked to leave the party.

A party goer who unknowingly filmed the fight said she had “no idea” what she was about to catch on camera.

Megan Roberts told Brighton Crown Court how she began filming because she liked the song, Toxic by Britney Spears, that was playing, before she realised what was going on.

Ms Roberts’ video footage played to jurors showed revellers just before midnight on July 22 dancing under disco lights in a marquee.

A fight is then visible in the background and the recording shortly ends.

She said shortly after filming the video, a DJ announcement was made that the police had been called and the party was over.

Party guest Harriet West told the court how she walked over to a high-vis man acting as security to ask about leaving the party when the police were on the way, but “just walked away” as she saw a boy on the ground near him.

She said: “He didn’t have a T-shirt on and he had blood all over his chest.

“I just left. The man in the high-vis was going on to his knees.”

The Argus: Charlie Cosser died aged 17Charlie Cosser died aged 17 (Image: Martin Cosser)

A friend of the defendant, also at the party, told the court he believed he saw a motionless Charlie being helped by two other people coming out of the marquee.

He told jurors: “I saw they were dragging him over, to the point I went over because I was concerned.

“They laid him down and there was blood all over his stomach.

“I told people to call an ambulance very quickly.”

Meanwhile, another party goer, Amelia Richards, told jurors that earlier in the night she had seen a group of three boys wearing dark tracksuits as she was walking towards the marquee, and overheard one of them saying about wanting to stab someone that night.

She said it was “something along the lines of ‘I’m going to stab someone tonight'”, but could not specifically recall the line.

Asked about who said it, she did not know which boy, adding: “It wasn’t like any of the farmers I knew who were there, the voice was more laddish.”

At the end of the night on the way back to her car, Ms Roberts also described how the atmosphere felt busy with people leaving and said you could feel something bad had happened, adding: “You could feel it when you were there, I knew something had happened but I didn’t know what.”

She had heard someone had been stabbed but said: “I didn’t actually really believe that could have happened.”

The prosecution had said Charlie was still conscious when police arrived at 12.30am and was able to tell them his name, address and date of birth.

He suffered a cardiac arrest on the way to hospital, with internal bleeding caused by a cut to his aorta, the main artery from the heart.

The teenager, from Milford, Surrey, died on July 25.

The defendant, now 17, who cannot be named for legal reasons due to his age, denies murdering Charlie and having a bladed article or point.

The trial continues.