It's 1984. I am working as a bookseller in one of the largest bookshops in England, Blackwell's in Broad Street, Oxford. In the days before the Internet, email and instantaneous real time stock information from the large book wholesalers became a part of the book trade landscape, booksellers relied upon annual print publications called Books in Print to allow them to see what was available in the market. 

By 1984, British Books in Print had expanded into four hefty volumes, each about 1,500 pages, double-columned, printed on paper that was Bible-thin and in tiny point size, and containing the bare bones of bibliographic data: author, title, ISBN, edition, publisher, in some cases the distributor, and the last known recommended retail price.

In 1984, the Net Book Agreement was still in force in the UK market, thereby prohibiting the bookseller from selling the book at a price less than that set by the publisher within a certain time frame. The explosion in book publishing that had been going on since the end of the war had driven the number of titles available in the UK market to around one million titles; yet the largest bookshops in the country, of which Blackwell's was one, could only hold around 200,000 titles on their shelves. Thus, over three-quarters of titles that were available for sale from the publishing industry were simply invisible to the book buying public.

Not only were these titles not stocked in the typical bookshop, they were not even visible other than in the pages of print-based trade catalogues. Jeff Bezos had yet to stir in earnest and invent a company called Amazon and a uniquely brilliant way of making all books in print available to anyone with a PC and something called an Internet connection.

Scroll back to the bookshop in 1984. I have a customer in front of me who wants to order a book that he cannot find on the five miles of shelves that Blackwell's boasts. Having consulted British Books in Print, I find the title and inform the customer that the book is in print and can be ordered. It will take about 4-5 weeks to arrive, at which he looks suitably impressed.

The order is duly placed by my filling in a three-part Shop Order Form; the bottom copy goes to the customer, the middle copy goes in a customer order file in my department and the top copy goes by internal post to the Shop Orders department who will have the job of working out the best way to place the order with the publisher.

After a period of a few weeks, a piece of card turns up in the post with a handwritten report on the status of the title. The publisher is reporting that the title is TOS. I explain to the customer that this means Temporarily Out of Stock, and that the publisher does not have copies on hand. I advise that we should leave the order live to see if this situation alters. After all it is temporary, so maybe the publisher will decide to make some more copies. Another few weeks pass, and another piece of card turns up with an update. This time it's the acronym RPUC.

I translate for the puzzled customer that this is book trade parlance for Reprint Under Consideration and means that the publisher concerned is thinking about printing some more but has yet to make a decision. The customer's face lightens a little with comprehension: perhaps he can still get a copy!

In accordance with my bookselling training, I advise that we should therefore probably leave the order live so that the publisher knows that there is at least one customer who wants to buy the book. More weeks pass by, and eventually another piece of card turns up in the post with a somewhat funereal look to it and the ominous OP acronym handwritten next to the title details. My customer's face falls because he knows what OP means. The book is dead and buried. It is an ex-book. It has breathed its last. I tell the customer, who by now has been waiting for this book for about three months, that the publisher has now made a decision: he will not be making any more copies. The demand in the market is not enough for the publisher to order a reprint quantity from his offset printer sufficiently large enough to make the financials work.

These are the days before digital printing, and the printer does not have the ability to print small quantities.  The printer needs a minimum order of 300 copies, and unfortunately there are not another 299 other customers like mine who want to buy the book. Despite there being a demand, the sale is lost to the bookseller, the publisher, the distributor, the printer, the author's agent and the author.

There is a disappointed book buyer who has to resort to rooting through the secondhand department at Blackwell's on the off chance that there is a spare copy. Of course, if he does find a copy, everyone in the chain apart from the bookseller will lose out on the sale.

Anyone who has worked in a bookshop can tell you a similar story of a sale that was lost.

Move the clock forward to 2007. The same customer is not even in a bookshop. He is online on Google Book Search. He finds the book within seconds and can even take a look at the content. He clicks on a link to one of the online booksellers listed on the screen next to the title. The book is a print on demand title although he does not know this. In fact, there are no copies physically held anywhere: this book is going to be made just for him.

The online bookseller processes the customer's order and sends the order via Electronic Data Interchange (EDI) that same day along with thousands of other orders to a print on demand business. The title is sitting in a digital library along with nearly half a million others.

The order is routed automatically to incredibly fast and powerful digital print engines that print his book along with thousands of others within a matter of seconds; other machines print the cover, and the internal workflow processes marry up the book cover and the book block. The cover is bound to the book and whizzed away by conveyor belt to rapid three knife trimming machines. The book is printed, finished and dispatched back to the online bookseller or direct to the customer within 24 hours.

Print on demand, the ability to print single copies from a virtual library when there is an order, is keeping books alive and in print to the benefit of all the players in the book supply chain. In addition, print on demand is starting to change fundamentally the very essence of the publishing model that has, since the days of Gutenberg, been premised on printing the book first and then trying to sell it. This shift is gathering pace as publishers begin to grasp the huge implications for the financial shape of their businesses.

The reduction or complete removal of the need to print speculative stock, tie up capital in the process and then warehouse it drives significant cost out of the traditional book publishing model, reduces business risk and allows a publisher to never miss a sale.

Print on demand is not only keeping books alive so that nothing is ever unavailable, it is also fuelling an explosion in new publishing models in self-publishing and content aggregation on a scale that is truly astonishing.

Literally thousands of titles a month are being made available in the market, and it is accelerating. The coalition between print on demand's ability to allow a single copy of a book to be supplied economically and the Internet bookselling model's ability to allow the individual customer to find and order these titles rapidly and easily is a match truly made in heaven.

But there is a third factor here that is sitting behind these two new business models. The concept of the long tail, first expressed by Chris Anderson of Wired Magazine, is the notion that there is an infinite long tail of demand for a product or service like a book or a piece of music. The traditional demand curve posited that there is a surge of demand for a new product; but after that initial surge, demand dies away to nothing. In fact, what appears to happen is that demand goes on ad infinitum but at a very low level. It is only with the coming together of print on demand and the Internet bookselling model that demand can start to be fulfilled and the long tail turned into a revenue stream.

The coalescing of print on demand, the Internet bookselling model and the long tail is starting to look like a perfect storm.