Europe's largest stem cell clinic which treats hundreds of British patients a year is at the centre of a scandal following the death of an 18-month-old baby who was given a controversial injection in the brain, it can be revealed. A doctor who worked at the clinic is now under criminal investigation over the child's death in August and the serious injury caused to a second child in another alleged botched operation three months earlier. The clinic has been accused of bungling the operations and failing to respond quickly enough when the surgery went wrong.