Louella Fletcher-Michie was “in all probability” already dead from a drug overdose in the final video taken of her by her boyfriend at a music festival, a court has heard.

But if the daughter of Holby City actor John Michie had received proper care hours earlier she would have had a “very good chance” of surviving the overdose at Bestival 2017, a medical expert told Winchester Crown Court.

Ms Fletcher-Michie was found dead at 1am on 11 September 2017, the day of her 25th birthday, in a wooded area about 400 metres from the festival’s medical tent, the jury has been told.

Her boyfriend Ceon Broughton, 29, of Enfield, north London, is now on trial accused of manslaughter and supplying her with class A drugs. He denies the charges.

Professor Charles Deakin, an NHS critical care consultant and a professor of resuscitation and prehospital emergency medicine at the University of Southampton, who analysed the extensive video footage recorded by Mr Broughton of Ms Fletcher-Michie after she had taken the drug 2C-P, told the court: “The two final videos, I would accept they are not very good quality, blurry and grainy.

In pictures: Manslaughter trial into Louella Michie's death Show all 6 1 /6 In pictures: Manslaughter trial into Louella Michie's death In pictures: Manslaughter trial into Louella Michie's death Ceon Broughton leaves Poole Magistrates' Court on 23 March, 2018. PA Archive/PA Images In pictures: Manslaughter trial into Louella Michie's death Family picture of Louella Fletcher-Michie, the daughter of Holby City actor John Michie, who was found dead after taking a party drug at Bestival on 11 September, 2017. Zoe Barling In pictures: Manslaughter trial into Louella Michie's death Louella Fletcher-Michie and Ceon Broughton were said to have been in an on-off relationship for a number of years. Instagram In pictures: Manslaughter trial into Louella Michie's death Ceon Broughton in the music video for his track 'Duracell'. CEONRPG In pictures: Manslaughter trial into Louella Michie's death John Michie attends the Inside Soap Awards, at Ministry Of Sound, in London, 21 October, 2013. Getty Images/Gareth Cattermole In pictures: Manslaughter trial into Louella Michie's death Ceon Broughton, 29, arrives at Winchester Crown Court on 4 February, 2019, where he is charged in connection with the death of Holby City actor John Michie's daughter Louella Fletcher-Michie. PA

“But from what I can ascertain, particularly at 23:25 [11.25pm] Louella’s skin appears blue grey, which is consistent with someone who has stopped breathing.

“I thought in terms of Louella’s physical appearance in the last [video] – mouth open, eyes rolled back – in all probability she was actually deceased at that stage. It is obviously difficult to tell for sure.”

Mr Broughton denies manslaughter and supplying class A drugs (PA)

The jury has been shown a number of videos including one lasting 50 minutes that started at 5.53pm. Professor Deakin described Ms Fletcher-Michie as “agitated and confused [and] shouting incoherently” in this early video.

He added that the sequence of videos as a whole suggested Ms Fletcher-Michie had suffered a “gradual demise”, rather a sudden disruption of heart rhythm that would have caused a near-instant collapse.

He told the court: “After looking at the videos, I am confident she would have stood a very good chance of surviving, if she had had appropriate care at the appropriate point.

“As long as she is actually breathing when found, I think the chance of surviving is very good. As long as you are breathing, the body is getting enough oxygen, you stand a very good chance of making a good recovery.”

By 8.18pm, he said, it was already clear Ms Fletcher-Michie was in need of urgent medical help.

Professor Deakin told the court: “By 20:18 she appears to be making incoherent noises. At that time, Louella is seriously unwell and in need of urgent medical care.”

But, he added: “By 23:24 there were no signs of life.”

Ms Fletcher-Michie’s death, he said, was the first reported case of a death caused by 2C-P.

Explaining that other patients had responded “very well” to treatment and had survived all six 2C-P overdoses described in the scientific literature, Professor Deakin said Ms Fletcher-Michie would have had about a 90 per cent of survival if medics had got to her by 9.10pm.

Under cross-examination by Stephen Kamlish QC, defending, he accepted that he could not say “beyond reasonable doubt” – which he quantified as above 95 per cent certainty – that Ms Fletcher-Michie would have survived if medics had got to her earlier.

He said: “I have never claimed that survival was a foregone conclusion. I have never said there is no doubt Louella would have survived [with earlier medical intervention].”

He added: “There are cases where people died from drug overdoses [despite receiving medical attention], but the vast majority of people who get into hospital with drug-related overdoses, the changes can be reversed and they can be saved.”