There was a point after Des died when I thought I'd never be happy again," says Ben. "But it's very difficult to become consumed by your grief when you've got a happy little boy in your life. Even at the darkest times, happy moments still can - and do - shine through.
It was one such moment that gave rise to the title of Ben's book.
On a day when Ben was 'sad to the point of absolute misery,' and the weather was equally miserable, he said to Jackson: "Put your hood up it's raining outside."
"It's not raining, Daddy, it's happy!" Jackson replied, snapping Ben out of his gloom in an instant.
It's not Raining Daddy, It's Happy by Benjamin Brooks-Dutton (Hodder & Stoughton) is available in Hardback and eBook editions from May 8 2014.