The writer talks about sexual violence in literature, the phone-hacking scandal – and why her new book might come as a surprise

PD James has been responsible for scores of rather nasty murders during the past five decades. But even one of the best imaginations in the whodunnit genre has to move with the times. While her most famous creation, policeman Adam Dalgliesh of New Scotland Yard, still has a huge and deeply loyal following, James has recently introduced gay characters into her novels; in another, an academic lost her job because the classics department made way for a media studies centre.

"What I do find difficult to understand is much of the behaviour and language of adolescents," she says. "I was researching what a 15-year-old would call the police. Is it Fizz or something? I can't keep up with it. In my day they were Bobbies."

James, AKA Phyllis Dorothy James, or Baroness James of Holland Park, OBE, is speaking to me from her home, just before she heads off to pick up a lifetime achievement award at a crime writing festival in Harrogate. "Being almost 91 makes receiving a lifetime achievement award all the more appropriate," James chuckles.

While Val McDermid and many contemporary female crime writers are increasingly developing plotlines involving serial killers and extremely violent sex crime, James can appear almost genteel and quaint in comparison. "My characters have sexual lives but there is no need for it to be so detailed. What I don't like is sexual gratuity. I don't want to write or read about lots of men writhing around."

Does James think female crime writers face particular barriers? She is reluctant to say, but reminds me of her female detective character Cordelia Gray, who has a more difficult time than her male contemporaries. "It is not a feminist plotline, but the reality is that a woman in her position would face difficulties that men would not. It is an inevitable part of her life."

For James, there are far more moral and ethical dilemmas to face today than when she was a young woman. She is concerned about the debate regarding assisted suicide and believes that it can be an encouragement to murder in some circumstances. "Death always advantages someone. I believe in the right of people who are living in torture to decide to end their lives but I am against any legal way to kill someone who wants to die. I would do it and face the consequences. I do not expect my country to change the law to suit my circumstances."

James took the Tory whip in the House of Lords, but insists she is not a "staunch Conservative". "I believe in the greatest possible freedom to the individual. I don't like this over-governing, and that is what we appear to have at present. We should have the freedom to make mistakes. My strongest belief is the importance of loving each other."

As she applies a stringent moral code in her novels, so she does in real life. We turn to the News International scandal. "Like all powerful people Murdoch has made enemies and there are many people who wish to keep the indignation going. But the Milly Dowler situation is appalling, and the person who gave the orders for her phone to be hacked can have no humanity at all. There is a dominant doctrine that says if you are the head of an organisation you fall on your sword when something goes wrong, and I think that is right. But it seems to no longer apply to bankers or politicians," she chuckles.

"And [former Met commissioner Sir Paul] Stephenson was guilty of what exactly?" she continues. "We've lost a good policeman."

Now, on days when she is working on a novel, James rises early and writes in longhand. Her secretary then types up her words, helps with emails and post, and organises James's diary. "I can barely do emails and am worse on my computer than a six-year-old," she says.

What is she currently writing? "A new novel, not Dalgliesh, which means that some people will be disappointed, but it is one I have been promising myself I would do for some time." Is it a departure from the Dalgliesh genre? Again she laughs. "Yes it is. I think you will be surprised.

"At my age the reality is that you just don't know what is around the corner. Once you are over 90 it is a bumpy ride."

• Theakstons Old Peculier Crime Writing festival runs until 24 July at the Old Swan Hotel, Harrogate