As a middle-aged man, he was doing odd jobs, including cleaning toilets, while by night he wrote his first novel, only to see it rejected by every major publisher. Undeterred, he borrowed money from family and friends to self-publish, and a year later has seen his book sell a staggering 1.7 million copies.

William P Young’s The Shack has become a publishing phenomenon in America, and is now due to hit Britain.

Having held the number one spot on The New York Times Best-Seller List for the past seven weeks, the book is now into its 14th print-run. It has been taken on by Hodder and Stoughton for Britain, where pre-sales have already reached 25,000 even before it reaches the shops tomorrow (17th).

Young, 53, wrote his novel - a parable about a grieving father who encounters God - as a gift for Christmas 2005 for his six children, now aged between 13 and 25.

They loved it and told their friends, who in turn also enthused. He distributed 15 copies bound in a local shop to family and friends who began recommending it to others.

When he began receiving enthusiastic emails from people he did not know, urging him to publish, he decided to have a go.

Speaking to The Times, he said: “I tried at least a couple of dozen, all major publishers. Very few even responded.”

Of those that wrote back, one stock excuse was: no niche for it. Others described it as “too edgy” or having “too much Jesus”.

Refusing to give up, he sought the advice of Wayne Jacobsen, a former pastor and author whom he had met. He sent him the manuscript with an apologetic letter.

Jacobsen was so taken with it that he and another former pastor and a film producer, Brad Cummings, collaborated with Young to publish it themselves, borrowing money or raiding their savings.

They thought they were being ambitious when they printed 11,000 copies to sell on the internet, but they sold out within four months, fuelled entirely by word-of-mouth. Then bookshops began to hear of the novel and ordered copies.

“It just snowballed,” Young said. “It unfolded in a wonderful grassroots kind of way.”

The Shack tells the story of a man whose young daughter is murdered and who, four years later, receives a note, apparently from God, inviting him back to the shack where his daughter’s blood had been discovered. He encounters God in the form of a larger-than-life Afro-Caribbean woman.

The shack is a metaphor for “the house inside a human being”, he said, “the place of a soul that gets damaged and twisted by what happens to you”. It is the inner dark place in which people store their hurt, their lies, their addictions and their secrets from the outside world, he added.

The novel is based on his personal experience of having to enter his own “shack” at the age of 38 and deal with painful memories from his childhood. Young was born in Canada to Christian missionaries who brought him as an infant to Dutch New Guinea to live with the stone age Dani tribe. While his parents devoted themselves to the community, unknown to them he suffered sexual abuse by the tribesmen from the age of four.

He went to 13 different schools. Later, he studied at a seminary in the US, but abandoned the career, and took to odd jobs.

In February, book sales had given him enough money to give up work. Now, having paid back loans to family and friends, he is on the way to becoming a millionaire. “It looks that way,” he joked.

Young has proved what can be done without a mainstream publisher. The novel had already sold a million copies and was already a The New York Times bestseller when, in May, the Hachette Book Group USA, of which Hodder is a division, agreed to print it.

Despite the success, The Shack has generated controversy in asking how God can exist in a world of unspeakable pain. While writers on Christian websites have described it as the best thing since C.S. Lewis, the novel has generated criticism for its edgy theology. Some Christian bookstores have refused to carry it.

American critics have been bowled over by its success. The New York Times said: “It is the most compelling example of how a word-of-mouth phenomenon can explode into a blockbuster.”

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