(As published in More Intelligent Life)

Sherlock Holmes is renowned for being super-rational. Yet his creator, Sir Arthur Conan Doyle, claimed to speak with the spirits of the dead. Andrew Lycett considers this paradox on the eve of the author's 150th birthday …

Sir Arthur Conan Doyle let me down. Shortly before I completed writing his biography, I went to a small corrugated building in North London to see if I could substantiate his belief in communication with the dead.

My destination was the Rochester Square Spiritualist Temple. As a plaque inside the door attests, Sir Arthur had helped finance its construction in the decade before his death in 1930. Having grown rich through his Sherlock Holmes stories, he had become the world's most famous exponent of spiritualism.

In my coat I carried a letter in Conan Doyle's hand. Perhaps I hoped this would give off some subtle communication to the temple's medium, who was busily delivering messages from the dead to members of the small, mainly female, congregation. I had hoped to learn more about the man, and maybe even something about myself.

But while the medium singled out people in the congregation to tell them details about themselves and their loved ones, she failed to alight on me. Despite her histrionic efforts to get in touch with 'spirit' (as she put it, without the definite article), she left my many queries unsolved and my scepticism fortified.

What a pity. It would have been sensational to round off my biography with definitive answers to nagging questions, such as: What was Holmes's actual relationship with Watson? And did the upright Sir Arthur have an adulterous affair with a younger woman while his first wife was dying of tuberculosis?

More apposite: how could Conan Doyle, a medical man steeped in empirical reasoning at Edinburgh University and the creator of a super-rational detective, have fallen for this mumbo jumbo? His support for spiritualism lent credence to some of the more outrageous frauds perpetrated on people desperately trying to get in touch with loved ones lost in the first world war. In his desire to prove the existence of spirits, he notoriously promoted two Yorkshire girls who, for a lark, claimed they had photographed the Cottingley Fairies (pictured).

On one level, his was the story of a lapsed Roman Catholic troubled by an alcoholic father and never quite able to cast off his sense of the supernatural. On another it was the intellectual journey of an inquisitive man, dissatisfied with Victorian materialism but intent on using its tools to examine alternative forms of consciousness. This was also a time when orthodox religion was giving way to Darwin and science.
 
As a doctor Conan Doyle was fascinated by early experiments in thought transference and healing through mesmerism and hypnotism. These were given an occult twist by early spiritualists, such as the Fox sisters from upstate New York, who won acclaim in the 1840s for their apparent ability to communicate with the dead through table-rapping (though they later confessed to fraud). America-based clairvoyants such as Daniel Dunglas Home crossed the Atlantic to become celebrities in Victorian Britain, where, despite being denounced by Robert Browning in his poem "Mr Sludge, 'the Medium'", they were even feted by scientists.

Paradoxically for an anti-materialist movement, spiritualism began boasting ever more tangible signs of such communication, including 'spirit photographs', ectoplasm and objects that floated round a room at a medium's behest. The conditions for fraud were widespread.

Conan Doyle became interested in the Society for Psychical Research (SPR), set up in 1882 to scientifically investigate paranormal phenomena, such as extra-sensory perception. But he found himself at odds with the SPR's objectivity. He felt he didn't need laboratory experiments to prove what he knew to be true.

After holding séances with his wife Jean to get in touch with members of their family killed in the first world war, Conan Doyle came out as a spiritualist. He claimed to converse with the spirits of the dead. Virtually abandoning Sherlock Holmes, Conan Doyle churned out books on spiritualism and addressed vast audiences around the world on the subject. He proudly adopted the sobriquet "the St Paul of the New Dispensation", ruffling some feathers along the way. In North America he clashed with Harry Houdini, an illusionist, who argued that all spiritualists' "tricks" could be replicated by a competent magician.

He was a crusader who enjoyed fighting for a minority cause. Shortly before his death in July 1930, he headed a spiritualists' delegation to the Home Secretary, J.R. Clynes, protesting against police harassment of mediums under antiquated witchcraft and vagrancy laws.

Almost eight decades later, spiritualism has seen off the threat of official persecution. (One of the last mediums to be tried for witchcraft in Britain was Helen Duncan in 1944, largely because she had seemed to imperil D-Day security by providing information about a sunken British ship.) Yet like many Victorian phenomena, spiritualism has fallen by the wayside. Those who are disenchanted with religion but keen on the supernatural may now content themselves with the new-age movement.

For all his commitment to spiritualism, Conan Doyle, who would have been 150 on May 22nd, was canny enough not to compromise Sherlock Holmes's credibility with it. Presented with evidence of the supernatural in "The Adventure of the Sussex Vampire", the great detective says, "This agency stands flat-footed upon the ground, and there it must remain. The world is big enough for us. No ghosts need apply."

(Andrew Lycett's "Conan Doyle: The Man Who Created Sherlock Holmes" is published by Weidenfeld & Nicolson in Britain and by Free Press in America. He recently spoke at a Sir Arthur Conan Doyle Sesquicentennial Celebration at Harvard University.)