The violent reality of 'Hellmarsh' - Britain's most secure prison - where Southport killer threw boiling water over guard and inmates have attacked more than 100 staff in a year
Widely considered Britain's most secure prison, the Category A institution in south-east London is known for holding extremely high risk offenders.
Widely considered Britain's most secure prison, the Category A institution in south-east London is known for holding extremely high risk offenders.
