A first-year Cambridge student was found naked and unconscious after taking a legal high and falling down a stairwell, an inquest has heard.

Thomas Millward was found injured at the bottom of stairs after police were called to 148-year-old Girton College on 5 March last year.

The 19-year-old had sustained a "traumatic" brain injury as a result of the fall and he died the following day at the city's Addenbrooke's hospital.

The inquest into his death heard that Millward could have taken his clothes off on the top floor of the college and chased someone down the stairs before the incident.

Millward's girlfriend, Daniella Mieloszyk, said she had obtained the drugs through a friend who bought them on the internet and the two of them had taken two tabs each.

She had told an officer at the scene that she had found drugs "on the floor at a festival" but said: "I don't know what it is and I wasn't going to take it."

In a statement, DS Andrew Gaunt-Warner of Cambridgeshire police said a quantity of drugs was found under Millward's bed.

Cambridgeshire coroner's court heard the engineering student, originally from Cheltenham, had a tendency to slide down the bannister of the stairs at the college on a daily basis.

Opening the inquest, Cambridgeshire assistant coroner Simon Milburn told the jury: "During the afternoon of 5 March, Millward and his girlfriend took a substance which was probably known as 1P-LSD.

"This was not a banned substance, it was what was referred to as a legal high."

The drug has since been banned.

Describing how the "talented sportsman" was discovered, Milburn said: "He was found lying naked at the foot of the stairwell – he appeared unconscious."

In her evidence, Mieloszyk said the effect of taking the drug was "overwhelming" and said: "I think we underestimated and naively didn't realise what it would be like."

After being left unable to "make decisions", the two students tried to get help from their friend, Tessa Duff.

Mieloszyk continued: "It was like we were shouting at ourselves to get help but we couldn't."

She told the jury how, some time later, she felt as though she had woken up and said: "As soon as I opened the door I saw another student called Hamish and I saw Thomas lying next to him.

"I thought it was like a dream and I just kept saying: 'We took a drug' as if we could realise it's not real."

She added she thought Millward would "walk down the stairs and say: 'Here I am.'"

Consultant neurosurgeon Stephen Price of Addenbrooke's hospital told the jury that he believed Millward died of a "severe and traumatic brain injury".

Millward's parents, Brian and Maisa Millward, said their son was a "sensational" student, and told the court his organs had been donated so that he could help others.

The inquest continues.