Queen of crime

I once subscribed to a collection of the complete works of Agatha Christie.  Many of them have now gone to other homes, but I still have a few.  I always thought she was badly served by the critics - her books were certainly not high literature, nor ever pretended to be, but they were straightforwardly and well written, and of course brilliantly plotted.  I was interested to read that my favourite story of hers also came top of a poll of the general public.  It's now known as "And Then There Were None", but those of my generation will remember it as "Ten Little (a word I'm not allowed to use these days)". The "plot twist" has been repeated several times since, but she was the first to come up with it.  That and "The Murder of Roger Ackroyd" were her two most superb plot inventions.