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Dick Francis coined intrigue from horse racing and Jilly Cooper from sex within racing, yet their efforts pale in comparison to the real-life workings of breeding thoroughbreds. No other sexual tryst can generate the sums of money Sea The Stars will command when he enters the covering barn next February.

In his first year Sea The Stars will earn the sort of royalties collected by both authors over their lifetimes. And all for the sake of a horse: the vehicle of four-legged dreams that has captivated minds for centuries.

The landed gentry dominated racing until the Second World War but their collective passing saw the new super-rich pursue the dream in their place. To them, these dreams have no price. As the late Lady Beaverbrook once observed: “I have all the art I need but nothing makes my heart beat like a horse.”

That is why hundreds of millions are spent annually by breeders when mating their mares to the stallions of their choice. It's a monster that feeds on itself: the more successful the stallion, the larger his fee, the more desirable he becomes, the better mares he gets, the more success he has.

Yet as David Redvers, proprietor of Tweenhills Stud, which stands three stallions, observes: “A well-bred colt which goes to stud has a one-in-ten chance of success. Otherwise it's one in fifty.” Sea The Stars is definitely of the one-in-ten variety - perhaps even one-in-five, given that he ticks all the right boxes.

Even then, luck will be the biggest influence on his prowess as a stallion. “A huge amount of it is down to sheer chance,” Redvers said. “There have been endless high-profile duds who didn't have the dominant gene. But that's the nature of the business. The day that someone can predict which stallions will succeed is the day the game will end.”

Breeders are thus a soothsayers' collective backing their judgment with hard cash. Numerous cottage industries have sprouted from the quest for an edge that may tilt the odds marginally in their favour. “Choosing the right stallion for your mare is an immensely complicated business,” said John Warren, bloodstock adviser to the Queen, who devises matings for more than 100 mares annually.

“There are so many angles to it,” Warren continued. “You look at nicks and crosses in the bloodlines, the temperament of the stallion in relation to your mare, their size , their physical shape - all sorts of things. I spend more time considering this than any other aspect of my work.”

Having made their selection, mare owners contact the stud housing their stallion of choice and negotiate over the advertised covering fee. A contract is drawn up, and in spring their mare will visit the stallion within days of giving birth to the foal she has carried for 11 months - itself the result of last year's covering.

Covering fees are payable in a number of different ways. The most common is under “October 1 terms”, which means that mares are scanned by ultrasound to determine pregnancy or otherwise on October 1. A successful pregnancy renders the fee payable, irrespective of whether the mare subsequently aborts.

Many contemporary breeders like to recoup some of their vast outlay on stallion fees by selling the subsequent progeny as a foal or yearling at auction. The best auctions are pure theatre. Giant human egos collide over the sight of the untested horse before them. A yearling will circle the auction ring for around two minutes, during which time bidding can rise beyond £1 million in rare instances.

Young horses not offered for sale are put into training by their owners, each of them hoping they have the next Sea The Stars on their hands. Generally, however, the economics are as prohibitive as one would expect of a dream factory.

From the moment a stallion completes the annual breeding process, the collective worth of those unborn foals is at its peak. Some mares will abort after the fee becomes payable, others will produce live foals with minor deformities that prevent them from racing at all.

More still produce offspring that fail to appeal to buyers at auction, in the process losing money on their production costs. Then follows the biggest financial drain on their collective value. Despite their regal bloodlines, the majority turn out to be plain slow when they reach the racecourse. One, perhaps two each year, will become worth eight-figure sums on their own stallion potential. In this way does the whole process renew itself.

When Sea The Stars takes his turn, the odds of him succeeding are greater now that they would have been 25 years ago. Back then, each stallion was bred to no more than 50 mares annually. After mishaps and natural wastage, around 30 of his sons and daughters would eventually reach the racetrack.

Now, however, the best stallions cover books of 200 mares, in the process greatly increasing their prospects of siring the champion required of them each season. Failure to do this results in their reputation suffering, their breeding fee being reduced, and breeders downgrading the quality of mare they send him. It is a slippery slope; one from which few recover.

“However good any stallion is,” Warren explained, “most of their runners will not be up to much. Even with Northern Dancer, only 25 per cent of his runners are black-type [superior] horses. And that's from breeding only to what I call to

A-mares. Sea The Stars will attract a lot of A-mares and that will increase his chances of success.”

The increased activity of the better stallions now makes it much harder for a bargain-basement stallion to hit the heights. Yet the nature of the business dictates that there is always one. Pivotal has been nothing short of a sensation. Having started life as a £6,000 stallion, he progressed through the ranks until, in 2007, his covering fee of £85,000 made him the most expensive stallion in Britain.

“This whole business is all about dreams,” Warren said. “No amount of research in planning matings or rearing horses guarantees anything. However much you spend, you cannot buy success.”