There was a time, just within living memory, when countless people were gripped by Spiritualism. It was comforting to think, especially after the slaughter of the First World War that the dead walked in a new place and could come back to earth to see loved ones for a quick chat and a squeeze.

In the early 1920s, mediums who claimed they were able to photograph auras, apparitions, séances, levitations and the spirits of the dead were in great demand, helped in part by the fanatical advocacy of Sir Arthur Conan Doyle who had turned turned towards Spiritualism several years earlier after having lost his son Kingsley, his brother, his two brothers-in-law and his two nephews in the bloody trenches and on the fields of the Great War.

Although many of the public believed the photographs mediums were producing to be fakes, it was hard getting evidence to prove it since they were understandably reluctant to sit for psychical scientists. Then one man exposed the movement for what it was.

Harry Price, was a 41-year old amateur photographer, paper bag salesman, freelance journalist, former Spiritualist and conjurer, who had successfully won membership to the Magic Circle, that exclusive body of magicians.

In early 1922, together with the Society for Psychical Research (SPR) Price used his Spiritualist contacts (blithely unaware of what he was up to) to lure the spirit photographer William 'Billy' Hope into a carefully crafted sting. Through this he was able to show the world that Hope's 'celestial' photographs were nothing more than pictures ripped from long forgotten periodicals, or family albums, which had been pasted onto photographic plates before a photograph was taken in the normal way.

It was enough to give Price the status of a minor celebrity; a position he had enjoyed some years earlier after a short journey into archaeology ended when experts, amazed at his luck in discovering rare artefacts, found he had forged a Roman silver ingot which on closer inspection turned out to be a crude slab of lead.

Following his success at unmasking Hope, Price was invited to accompany the SPR foreign research officer Eric 'Dirty Ding' Dingwall to witness the astonishing feats of an Austrian medium named Willi Schneider, who claimed to have the gift of communicating with the spirit world via his guide Lola, the former mistress of Ludvig the First, the blind king of Bavaria.

When Willi produced such remarkable phenomena as invisible hands playing an accordion, discarnate lungs puffing chilly breath through witnesses' hair and a crawling disembodied hand, Price set himself the task of establishing a laboratory in Britain that would test mediums and supply the world with unknown facts about the paranormal.

He got off to a remarkable start by being told about a 21-year untried medium called Stella Cranshaw, a tractable young nurse who claimed to possess supernatural powers. In a series of exhaustive experiments with Price, she was reported to be able to summon a violent force that broke tables, chairs levitated, and mysterious objects were seen to crawl along the floor of séance rooms: and through her the dead prophesised the future.

The séances with Stella were reported as a world first, but other psychical investigators, notably those from the Society for Psychical Research distrusted Price's experiments and as a result he found himself marginalized, a situation he responded to with calculated insults, attributing the Society's attacks on his character to sectarian jealously.

After falling foul of the SPR, Harry had several attempts at trying to prise money from leading spiritualist organisations with a view to establishing his own psychical organisation.

In 1925, he managed to form the National Laboratory of Psychical Research (NLPR) a project backed by the London Spiritualist Alliance.

With his celebrity rising, he made friendships with well-known magicians, scientists and show people including Harry Houdini, a relationship that petered out a few years later after accusations of fraud.

But that did not matter. At the NLPR, Price had the ear of eminent men of letters and since he now regarded life after death as proven, had become a friend of Conan Doyle, and was given the necessary money by wealthy supporters to investigate areas of the occult others had only dreamt of.

He attempted to contact the planet Mars, a fascination that had begun with the late Victorians after the Italian astronomer Schiaparelli had claimed to see canals on the planet through his telescope, a claim supported by his colleague Camille Flammarion.

At first Price used clairvoyants who claimed a familiarity with the solar system and stars, then he used an odd invention made by a City of London solicitor to try to contact Martian savages. When this proved inconclusive he travelled to the Jungfraujoch in Switzerland where he considered making an attempt to contact the Red Planet using a huge beam of light but the project was abandoned on account of the cost.

Each experiment at the NLPR was too preposterous, too remarkable for any sensible person to ignore. Every strange incident or miserable plaything of the dead was publicised to keep pace with the public's appetite, which Price had whetted.

He was rapidly becoming the natural leader for a nation in thrall of what happened to the soul after death. No newspaper report or broadcast on a haunted house was complete without Harry's thoughts about the matter. He had a status and reputation that no ghost hunter of today can hope to share.

He claimed that his findings were bolstered through his training as a scientist and engineer but in reality, the man who had left school at 15, was an academic failure. His scientific methods were nothing more than an act using scientific apparatus and the trappings of a chemical laboratory merely to convince people that he was a scientist.

He thought instinctively and impulsively and instead of trying to disprove his theories, he sought only to prove them. At one stage in his career, he believed he had discovered the very substance that ghosts were made of and thought it might be possible to recreate them from a piece of regurgitated cheesecloth, iron filings and albumen.

He sought out a talking mongoose on the Isle of Man called Gef who it was said spoke several languages, could recite poetry, travelled around the island on a bus to bring back gossip and was partial to cream buns.

Price also set out to prove the uselessness of transcendental magic by showing how turning a goat into a handsome man on top of the Harz mountains in Germany was bound to fail.

It did, but he got to smear the chest of an attractive girl with a sticky black substance, which he claimed was an alchemical ointment though The Times described it as 'looking and smelling exactly like boot polish.' The event though did bring him an appreciative audience largely made up of prominent Nazi's.

Impatient for academic and financial success, which had eluded him in Britain, Price was wooed by the Third Reich to establish an institute for psychical research, a project Hitler took great personal interest in. It was an idea he had promised Erik Jan Hanussen, his personal seer, before he had him murdered.

When war looked inevitable, and warned off by MI5, the idea was dropped but not before Price had written a letter asking Hitler if he could witness the 1939 Nuremberg Rally 'in some comfort' planned for that August. Following the failed airlift of his laboratory to Bonn, Price's offices in London were closed, the contents crated up and transferred to the University of London after his friend, the philosopher Cyril Joad had successfully negotiated their safe berth.

Now on his own, Price, still selling paper bags for a living and without money to fund experiments, began to invent phenomena to supplement his earnings. Perhaps the best example of this is the haunting of Borley Rectory in Essex. It was a time when he would do anything for money.

Since his death in 1948, two biographies have been published. Paul Tabori his literary executor paved the way with his Biography of a Ghost Hunter, a book written under strict terms of engagement with Harry's widow so anything that deviated from her husband's carefully crafted autobiography was snuffed out and replaced with tall 'facts.'

In 1978, Trevor H Hall, a successful businessman and author on the esoteric, published a revised version of Harry's life, Search for Harry Price. Though he discovered a lot Price had written was invented, Hall just skimmed the surface of who the real Harry Price was partly due to the sheer quantity of documents his subject had bequeathed to the University of London. Only in 2005, fifty-seven years after Price's death, was his vast archive at last catalogued; a project undertaken by Lesley Price (no relation) and Stefan Dicker at the university's Special Collections Unit and this has helped considerably in writing my recent biography, Harry Price: The Psychic Detective, published by Sutton.

It is not a book about psychical research as such. I have aimed to understand Harry Price and his complex personality. I have tried to give him a voice by searching through thousands of documents in his archive and elsewhere.

I believe that the Harry Price I have written about is the closest the reader can come to knowing who he really was.