As the chilly air of autumn sends a shiver down the spine and the spirits stir for Halloween, Sussex author James Herbert is set to haunt us with two scary ghost stories.

The BBC will broadcast an adaptation of the horror writer’s best-selling 2006 haunted house novel The Secret Of Crickley Hall over Halloween, starring Suranne Jones. It comes just a few weeks after his long-awaited novel Ash was published, the third in his series of stories featuring ghost hunter and parapsychologist David Ash and a controversial blending of fact and fiction.

Ash is sent to investigate hauntings at a secretive Scottish castle run as a sanctuary for lost souls by a shadowy but influential consortium. Inside its walls he discovers a gruesome collection of fugitives, some fictional, but most infamous real-life criminals who are believed by society to be long dead.

The author, best known for his novels The Fog and The Rats, and himself a qualified private detective, has speculated on their lives after their “deaths” – and admits he had great fun doing it.

“I chose the famous names by watching the press and the media and the TV, and these stories came up, and I like to speculate,” he says with a hint of mischief.

“I’m a great one for reading between the lines. But I don’t say that this is what happened – it’s up to the reader to make up their own mind, to decide what is fact, what is fiction and what is faction.”

Fascinated by the comment, “there are dark forces at work in this country, about which we know little”, alleged to have been made by the Queen to Paul Burrell, Princess Diana’s butler, Mr Herbert speculates that the “dark forces” aren’t necessarily something supernatural but could just as easily be a sinister consortium of influential wealthy business people.

It led him to involve the Royal Family in what is probably one of the most controversial story lines of the novel.

Princely warning

Mr Herbert draws on an incident early on in the marriage between Prince Charles and Princess Diana to reach a shocking conclusion.

He warned Prince Charles ahead of time, says London-born Mr Herbert, who lives near Henfield.

Presented with an OBE by the Prince of Wales in 2010, the author, with the novel’s plot already well developed, told him he had a new book coming out.

“Charles had pinned the OBE on to me and I told that he is in my book,”says Mr Herbert. “He really blanched – he went red, then white. But I said to him, ‘You come out of it OK’.”

Insisting he is actually a monarchist, Mr Herbert dismisses the possibility that Princes William and Harry could be distressed by the story line.

“They have got to realise that it is purely fiction,” he says. “I make no claims. I would hate to upset them, because I like them.”

He proves it, says Mr Herbert, by including a conversation in Ash which trashes media speculation about Harry’s parentage and praises both Prince Charles and Princess Diana.

Ash arrives six years after his last novel, The Secret Of Crickley Hall, proving a long wait for James Herbert fans.

“When I had delivered the manuscript of The Secret Of Crickley Hall to my publishers, I was taken ill on the journey back,” explains Mr Herbert.

“Everything is fine now and I was able to do the research for Ash. It is my most researched book and the publisher extended the publication date because it is such a big book.”

He continued to work on the book through a second bout of illness, driven by the work ethic instilled in him by his parents.

“I have worked so goddam hard all my life,” he says. “When I write, I’m so intense – and it’s not something I do for the money. It’s a vocation.”