An 18-year-old straight-A student fell from his bedroom window to his death, a coroner's court heard on Wednesday last week.

Stephen Smith had been behaving strangely after returning home from a week-long management course in Worcestershire on October 14 last year.

"He was chatting quite fast, very bubbly, thinking in a strange way just gabbling," said Stephen's 20-year-old brother James, a Cambridge University student.

"He was in tears at times, through elation rather than something sad."

Later that evening, at the cinema, James said that his brother's legs 'were shaking very violently'.

Stephen's father Martin, a Borehamwood-based solicitor, ruled out the possibility that Stephen may have wanted to harm himself.

He believed that Pro-Plus caffeine tablets may have affected Stephen's behaviour.

A toxicology report did not confirm this, but coroner Dr William Dolman noted that Stephen had received 20 units of blood in hospital prior to the analysis, which may have affected its outcome.

On the night of his death, Stephen had gone to bed at around 11.40pm.

Just after midnight, his brother James, his 16-year-old sister Emily and a friend heard a 'muffled cry and a thud outside'.

Minutes later, James broke down the locked door of his brother's room, looked out of the window and saw him lying on the driveway.

An ambulance took Stephen to Barnet Hospital, but he never regained consciousness.

He died from massive head injuries.

A verdict of accidental death was recorded.

After the inquest, Martin Smith said: "It's not something you can ever put behind you. You think about them every day.

"Not just once or twice, you think about them all day long and go to bed thinking about them."