My first and only experience with a Ouija board occurred when I was 11, at a friend’s house. It was good, spooky fun until it wasn’t. I recall movement and the start of a message before we recoiled from the board. Later that evening, I learned that my grandfather had died. While I realise now that a boy with a terminally ill relative and a lurid imagination was not the most reliable witness, I remember wanting to believe that I’d had a brush with the uncanny.

When Times journalist Ben Machell’s dying grandmother bequeathed him a crystal ball, he began idly searching for mediums and happened across the work of a man named Tony Cornell. Between 1952 and 2004, Cornell worked (unpaid and to the detriment of two marriages) for the Society for Psychical Research (SPR). Weeding out deception and delusion from accounts of paranormal activity to find out what, if anything, remained, Britain’s most diligent parapsychologist was more claims adjuster than ghostbuster. His answering machine filled up with pleas to investigate strange happenings around the country: a trawlerman mauled by an invisible hound, a house that bled water, a rural bungalow plagued by fires and expiring pets.

Machell has honoured Cornell with an entrancing biography. Drawing on boxes of tapes and documents, an unpublished memoir and interviews with relatives and contemporaries, he hears “the steady voice of a rational man methodically tapping the wall between reality and something else”. Cornell’s approach was approvingly described as “probing-doubt”: curious without being credulous, sensitive yet rigorous. In 1977, he clashed with two SPR colleagues over the infamous Enfield poltergeist: a hoax, he decided, but they got a bestselling book out of it while Cornell’s work, Machell writes, was largely “unheralded, unrewarded and appreciated only by a small group of people”. Machell’s elegantly thrilling yarn encompasses the broad history of paranormal research in the UK. In the middle of the 19th century, the tension between science and religion inspired a craze for “proof” of life after death in the form of spiritualism – seances, clairvoyants, automatic writing – and a subsequent desire to assess its veracity. The SPR was founded in 1882, in a “spirit of exact and unimpassioned inquiry”. Its members, including Lewis Carroll, future prime minister Arthur Balfour and psychologist William James, pioneered concepts such as telepathy and ectoplasm while exposing fraudulent mediums and “spirit photographers”.

The SPR proved so adept at debunking charlatans that Arthur Conan Doyle led a mass exodus of aggrieved spiritualists in 1930. The author’s nemesis was the American researcher JB Rhine, whose new field of parapsychology focused on psychic phenomena rather than the spirit realm. A poltergeist, for example, might actually be “recurrent spontaneous psychokinesis” – the violent discharge of mental energy by the living. Rhine’s secular approach appealed to Soviet materialists, who explored telepathy as a potential cold war weapon. The physiologist Leonid Vasiliev, whom Tony Cornell visited in Leningrad in 1962, possibly at the behest of MI6, claimed that explaining extrasensory perception would be as significant as discovering atomic energy.

The more concepts such as telekinesis excited the public, though, the more uneasy the group’s rationalist wing became. In the 1970s, the decade of Uri Geller and Stephen King’s Carrie, Cornell’s mentor Eric Dingwall snapped and repudiated parapsychology for feeding a “new occultism”. Yet Cornell persisted. Even as he exposed numerous instances of mischief, attention-seeking and hallucination, he personally encountered a handful of phenomena that defied rational explanation. It was a mind-boggling experience in postwar India, too good to spoil here, that set him on this path in the first place. He still sought answers.

During the 1990s, to his surprise, Cornell’s answering machine fell silent. He wondered whether conspiracy theories had supplanted the paranormal in the public imagination, or perhaps digital distractions had dulled our receptivity to psychic disturbances. But had he not died in 2010, he would have seen a new generation of ghost hunters do a roaring trade on YouTube, where there is no financial incentive for his brand of cautious analysis. As Dingwall feared, entertainment has trumped genuine investigation.

Like many a biographer, Machell falls half in love with his subject. Cornell was respected within the SPR for his diplomacy and his “consistent willingness to be wrong”. Parapsychology may not be widely accepted as a branch of science, but Cornell had a true scientist’s commitment to doubt and impartiality. At a time when beliefs leave facts in the dust, it’s easy to share Machell’s admiration for a man who was willing to say: “I don’t know.”