I just finished reading PD James’ latest mystery, The Lighthouse, which came out last year. And I must admit I am a little disappointed.

Not that I would have missed it for anything in the world.

PD James is too good a writer to ever really let down her readers. The writing is as assured as ever, picturesque, elegant, smooth, the sentences beautifully constructed, unblemished by split infinitives like the one I used in the previous sentence. This is British writing almost at its very best, in the tradition of Graham Greene, quiet, understated, and yet vivid and seamless. Once I picked up this book, it was impossible to put down.

Commander Adam Dalgliesh, the Scotland Yard detective who has come a long way since he appeared in James’ first novel, Cover Her Face, in 1962, is called upon to investigate the mysterious death of a famous novelist on a little island off the coast of Cornwall.

There are only a handful of people on the island, which is privately owned and does not admit strangers. So the murderer cannot be an outsider. That makes it like an Agatha Christie mystery. And, like Christie, James profiles each of the suspects, their background and motivations, in considerable detail.

But while the plot seems like vintage Christie, there are differences. The story is set in Britain today. An outbreak of Sars, brought in by a visitor from Hong Kong, cuts off the island after the novelist’s death, hampering investigations. Pre-marital sex and same-sex relationships are accepted, unlike in Christie’s time. A peripheral character, who makes a fleeting appearance, is a lesbian living with her partner. James does not frown upon such relationships. She has kept up with the world which must have changed considerably since she was born 85 years ago.

It is remarkable how modern and up-to-date she is, given the fact that she will be celebrating her 86th birthday on Aug 3 this year.

But she has dated too, which is inevitable when you are that old. There is a puritanical streak behind that modern sensibility. She may accept  pre-marital and same-sex relationships but so restrained in her descriptions of the emotion of love and the act of sex that she would have been better off leaving them out of her novel. But she can’t. Dalgliesh has to have a romantic interest to make him more human. Yet the way James describes Dalgliesh’s feelings for the woman he wants to marry and her feelings for him, it is too sketchy and idealised.

And the weakest scene is the denouement, where the murderer is caught. As Dalgliesh is laid up with Sars, the arrest has to be made by his two assistants, Kate and Benton-Smith. The scene is obviously made for television. Kate has to strip to her bras and panties and greased up with Vaseline by Benton-Smith to wriggle through a narrow opening into the lighthouse where the murderer is holed up, threatening to throw a teenage girl from the top floor if the detectives try to arrest him. Kate has to get in through the only opening to unlock the lighthouse door and let in Benton-Smith who can’t get in otherwise. But the scene jars with the rest of the novel.

The Lighthouse is a serious earnest novel with plenty to say about crime, life, society, and the “ruthlessness” it takes for people to succeed in life. James has little sympathy for losers and underachievers. That comes out clearly in the end. I can’t say more, for that will give the plot away. But it makes James less attractive as a writer and a person.

One more complaint: She repeatedly reminds the reader that Dalgliesh is a poet as well as a novelist. But she never treats us to a sampling of his work.

James is comfortable describing a world where people listen to classical music, go to Oxford or Cambridge, quote Shakespeare in everyday life and have three-course dinners. That is natural for a woman who is an old-school Conservative and a life peer.

I preferred Death In Holy Orders, the previous Adam Dalgliesh mystery I read, which was published in 2001. I have yet to read The Murder Room, which came out in 2003.