Twenty years ago, before the big adaptations of classics that would make him a household name, Andrew Davies adapted a little known thriller for BBC Television.

Mother Love by Domini Taylor. The series was a huge hit and a critical success.

And I missed it – I think it coincided with the exam season. I waited for a repeat, but it never came. I looked out for the book, but it had fallen out of print and a copy didn’t turn up. Until last year, when I saw an extremely tatty paperback on sale for a mere 10p. I snapped it up.

It proved to be very readable.

The story began with Kit and Angela. Two young Londoners, both professionals, both from affluent backgrounds. They fell in love, and their relationship moved forward quickly. There was just one thing that bothered Angela: Kit’s reluctance to introduce her to his family.

Helena was fragile. The end of her marriage had destroyed her, and now Kit was all she had. She didn’t know that Kit had rebuilt his relationship with his father, and that he was on friendly terms with his father’s new family. She mustn’t know; she had attempted suicide before; she had to be protected.

The situation was ludicrous, and yet it was easy to see how it had come about, why everyone played along.

In the end Angela had to meet Angela, and after a difficult start Helena accepted her. She saw a new family, new possibilities.

But maybe Helena wasn’t as fragile as she seemed. Maybe she was disturbed. Maybe she would do anything to serve her own interests …

A single, horrible revelation demonstrated that Helena was very dangerous and very clever.

I saw that, but nobody else did.

When Kit and Angela married, when they had children, more and more effort, had to be put into protecting Helena. I understood why Kit’s family had to do this, but I couldn’t quite understand why Angela’s family did. Why nobody put their foot down, said the situation was ridiculous, suggested that if Helena couldn’t accept Kit seeing his father she needed professional help …

Eventually there was a slip. Helena learned that a friend she thought was loyal to her was a friend to Kit’s father’s family too. She lashes out, and the consequences are devastating. And, because Helena is so very clever, nothing is linked to her.

I was stunned by what happened, by the cleverness of the plot and by the horror of what happened, but I was bothered by the slip. Of course there had to be a slip one day, but I didn’t believe that people who had taken such care for so long would make such an elementary mistake.

Life went on. Alex’s father, a successful conductor, married a Hollywood actress and there was huge media interest in the couple. The things that had to be done to keep Kit’s relationship with his father secret from Helena became ludicrous. As did the idea that absolutely everyone would play along.

But I was hooked. Helena was such an extraordinary creation, the story was compelling,and I did want to know how it would all end.

There was, of course, another slip. Helena finally found out that Kit had been seeing his father, that he and Angela had been deceiving her for a long, long time.

Who would she turn on this time?

The story ends with wonderful, breathtaking, high drama.

Mother Love is a clever, dark, glossy thriller, and Helena really is an extraordinary creation.

But it is dated, and I had to suspend belief a little too much.

Very readable though, and I can see that it would have made great television …