'We're heartbroken', parents Tom Evans and Katie James say.
Tom Evans praised staff treating 23-month-old for their 'professionalism and dignity'.
An air ambulance was on standby 'at the request of the Pope'.
Judge says case of terminally-ill boy has reached its ‘final chapter’.
Doctors says that continuing life-support treatment is not in the child’s best interests.
'We are not willing to let him die.'