He died of positional asphyxia at Rainsbrook STC in April 2004.

After an inquest lasting seven weeks, a jury returned a verdict of unlawful killing, citing " positional asphyxia".

In 16 of those cases, restraint was linked directly to the death, and four were classed as " positional asphyxia".

He was told: "If you can talk, you can breathe." He died from positional asphyxia, choking on his own vomit.

The risks of positional asphyxia have been well-known since the April 2004 restraint death of 15-year-old Gareth Myatt in the secure training centre at Rainsbrook.