If, like many people, you’ve watched the four-part series The Sixth Commandment on BBC1 or on iPlayer this month, you can’t have failed to have been moved by the true story of the murders of two pensioners by a manipulative psychopath.

But it wasn’t the absent parent that moved me in The Little Mermaid, it was something much closer to home.

The very clever device the Director, Florian Zeller, employed was to tell the story as seen through the lens of dementia, so we could experience the confusion and frustration felt by the father.