The knock on the door came at 5.30am, and it changed David Parfett’s life for ever. “I looked out and there was a police car outside,” he recalls. “At that moment, I knew.” What David knew was that his son, Tom – who loved sing-alongs in the car and his family – had taken his own life at the age of 22. David had been worried about Tom, who was autistic, lived with anxiety and obsessive compulsive disorder and had been sectioned for talking about suicide. But the day before he died, in October