When the police unlocked my ­cellar door and found me hiding there, it was my son who quickly took the pen knife from my hand.

I had used it but in only a token manner: the wound on my neck was little more than a scratch.

My mind had pictured the blade well through the skin, cutting my jugular vein, but the reality of my intended act had brought unexpected pain, and by reflex, I stopped pushing.

There was a degree of planning, but thankfully, my brain was disordered, and I had failed.