Champion Frankel has controversially been rated the greatest horse to ever race with Black Caviar also high on the list following the release of the World Thoroughbred Rankings.

The British superstar was given a mark of 140, 10 ranking points more than Black Caviar.

The latest assessment places Frankel as the highest-rated horse since the World Thoroughbred Rankings system began in 1977.

But while Frankel was elevated to top billing, several stars of old had their ratings downgraded included Dancing Brave who dropped from 141 to 138.

Black Caviar was rated the equal third best horse of 2012, earning praise from senior Irish handicapper Garry O'Gorman who described her as "the female Frankel".

Gorman is part of the group of handicappers across Europe who comprise the ranking committee and they have long voiced their concern that methods have evolved over the last 35 years, and that some horses have ended up with figures which are slightly too high.

That was the reason given for their adjustments to some historical figures, although the decision didn't sit well with everyone, including Dancing Brave's trainer Guy Harwood.

"It sounds to be an extraordinary thing to do, to downgrade a horse," Harwood told England's Sky Sports News radio.

"I don't know you can do that, having used experts to give you an opinion.

"At the end of the day, trying to compare one great horse to another great horse is not a clever thing to do.

"I think it's absurd."

With Frankel retired, French star Cirrus Des Aigles is the highest-rated horse in training on 131, just ahead of Black Caviar.

Teddy Grimthorpe, racing manager for Frankel's owner, was delighted with Frankel's elevation to the best horse in history.

"He has set new standards by which others will be judged," Grimthorpe said.

"Frankel is going to start covering mares next month and he seems to be looking forward to it."

So You Think was rated 126 after signing off his racing career with victory in the Prince of Wales's Stakes at Royal Ascot.