'Most of us know very little about mental illness'
14 August 2014 Last updated at 10:37 BST
Adrian Strain, whose 34-year-old son Martin recently took his own life, told the Today programme that people were shocked to find out that Martin had suffered from depression for many years, considering he was a very "jolly person".
"Most of us know very little about mental illness," he explained.
"I always worry whether or not we could have done more. "
First broadcast on BBC Radio 4's Today programme on Thursday 14 August.