Suffered a brain injury at four-months old, when his baby carriage was struck by a taxi. The most serious of his injuries was Hydrocephalus (commonly known as water on the brain). His father, author
Roald Dahl, got together with a pair of friends -- a neurosurgeon and an engineer -- and created a device called the Wade-Dahl-Till valve to alleviate cranial pressure. The device allowed Theo and others suffering from Hydrocephalus to recover from their injuries.