The £150m stud: Frankel retires undefeated - now the frolics begin!

He is hailed The Greatest after cruising to his 14th successive win yesterday. Now his owners hope he can emulate the multimillion-pound breeding success of his forefathers

Basking in the glory of an undefeated 14-race career yesterday and winning £3m over the past three seasons, Frankel could be forgiven for wanting to relax. But, in truth, his real money-making exploits are only just beginning.

The four-year-old bay sealed his claim to the title of the world's greatest racehorse in front of the Queen at Ascot, winning the Champion Stakes. Plaudits flooded in, with Frankie Dettori, Britain's best-known jockey, saying: "He's been an amazing story and an amazing horse. He doesn't just win, he destroys the field." Pat Eddery, the former champion jockey who rode Dancing Brave to victory in the Arc de Triomphe in 1986, added: "He's a very exciting horse, he's unbeaten and has won a lot of Group Ones – he has to be there with the very best." Aidan O'Brien, arguably the world's best trainer, was succinct: "One word describes him – incredible. He's the most incredible horse we have ever seen. "

Sir Michael Stoute, the Queen's trainer, paid tribute to Henry Cecil, Frankel's trainer. "Henry and his team have handled [the horse] impeccably," he said. "When he accelerates he destroys the opposition in about 100 yards. He is a magnificent racing machine."

Frankel's owner, Prince Khalid Abdullah of Saudi Arabia can now look forward to a much bigger prize than any race could offer: two decades of the fees his mount could realise at stud, with practically every major horse breeder in the world desperate for a share of his horse's unbeatability,.

Provided his first offspring race well, he could earn more than £150m siring the next generation of thoroughbreds. The star of Prince Khalid's stable is predicted to command stud fees of up to £150,000 – and stallions can cover around 200 mares a season. Lord Grimthorpe, the prince's racing manager, said: "Some of the greatest breeders on earth are queuing up to send their mares."

Frankel is descended from greatness: his ancestors have been crowned leading sire in Great Britain and Ireland – determined by the amount of prize money won by the sire's progeny – in 19 of the last 20 years. His father is the 2001 Epsom Derby winner Galileo, the most influential stallion of his generation. Officially Galileo's stud fees are private, though according to reports the stallion can earn £120,000 per foal – and he produced a record 214 in 2011.

Fees can often decline as the stallions get older, yet the 14-year-old Galileo still dominated the yearling sales two weeks ago at Tattersalls, Europe's biggest bloodstock auction house, in Newmarket. A yearling colt of his was sold for £2.6m to the Qatari royal Sheikh Fahad bin Abdullah Al Thani on the last day of the auction - the most this year and the third-highest price paid for a one-year-old untrained racehorse in Europe. Two fillies sired by Galileo fetched £1.4m and £1.6m respectively.

Frankel's mother, Kind, was a sprinter and five-time listed race winner who has become a successful broodmare. His grandparents include Sadler's Wells, a middle-distance specialist and the world's most dominant sire of the past 25 years, and Urban Sea, who produced another recent great, Sea the Stars. He is also the grandson of Danehill, the most successful sire of all time who was leading sire in Australia, France and Great Britain and Ireland on 15 occasions.

But not all racing greats perform equally well at stud. Aidan O'Brien's 2,000 Guineas winner George Washington was found to have fertility problems and returned to racing, but was later put down on track after injuring himself at the Breeder's Cup Classic in 2007.

"It's a very unforgiving business," said Harry Herbert, the chairman of British Bloodstock Marketing. "If he doesn't come up with some really exciting horses, Frankel's followers will know their fate very quickly."

Due to a changing economy, Frankel may never become the most valuable racehorse in history – his great-grandfather Northern Dancer can lay claim to that. It cost $500,000 (£310,000) to breed with the Canadian colt in the mid-1980s.

John Sparkman, a private bloodstock consultant, said horses in general are not worth as much now as at the turn of the century. "The market nowadays simply won't stand for it," he added, saying the maximum Frankel could command in today's economic climate would be $200,000.

Debate continued to rage yesterday as to whether Frankel, who retires at the top of the World Thoroughbred Rankings, is the greatest ever. Many find it difficult to compare Frankel with Sea Bird and Dancing Brave, who both won the Prix de l'Arc de Triomphe, Europe's blue riband event.

Frankel's lack of rivals on the course has also been a cause of muttering among critics – just five horses lined up against him at Ascot yesterday. By comparison, Dancing Brave's 1986 Arc victory at Longchamp saw him beat 14 rivals, including Derby winners from around Europe such as the horse he narrowly lost to at Epsom, Shahrastani, the French colt Bering and the German champion Acatenango, in a record time.

By not retiring him last year, experts predict, Prince Khalid has missed out on £20m in stud fees. It seems entirely likely that, barring catastrophe, Frankel will step up the pace once again to follow in his father's lucrative footsteps.

The greatest on four legs?

Frankel's trainer Henry Cecil was adamant: "He's the best I've ever seen. I'd be surprised if there's ever been any better." Here are some that might measure up:

Shergar "Shergar wins. You need a telescope to see the rest," said the commentator Peter Bromley after the 1981 Epsom Derby.

Sea Bird The French wonder horse won seven of his eight races from 1964-65.

Brigadier Gerard Very popular horse, winning 17 of his 18 races.

Man O'War Voted the greatest American thoroughbred of the 20th century.

Dancing Brave Greville Starkey and Pat Eddery shared his victories.

Mill Reef Won 12 of 14 starts in 1971.

Nijinsky The last horse to win the Triple Crown in the UK, in 1970.

Secretariat His records in the US Triple Crown in 1973 still stand.