Multiple Group One winning mare More Joyous has been retired and will be sent to England to be mated with Frankel.

Her last race was shrouded in controversy and sparked a much publicised stewards inquiry when her owner John Singleton sacked trainer Gai Waterhouse in a television interview after More Joyous ran second last in the All Aged Stakes on April 27.

He accused her bookmaker son Tom of passing on information in the days before the race that the mare could not win.

Tom Waterhouse was cleared of any wrongdoing, while Singleton was fined $15,000 after pleading guilty to charges of improper conduct.

The long-time friendship between Waterhouse and Singleton started unravelling last spring when the trainer selected barrier 11 for More Joyous in the Cox Plate against his wishes.

It broke down irretrievably after the All Aged Stakes at Randwick and Singleton removed his remaining horses from her care.

Singleton's racing manager Duncan Grimley said More Joyous had nothing left to prove on the track and would be accompanied to England by stakes winner More Strawberries who is also to be mated with Frankel.

"More Joyous is special to John because not only did he breed her to win eight Group One races but he also raced her mother, Sunday Joy," Grimley said.

Frankel, who retired unbeaten last year as the highest ranked horse since the introduction of international ratings, will serve a limited number of mares to southern hemisphere time in September.

Singleton had already booked More Joyous to be served either this year or next and made the decision on Sunday that her racing career was over.

More Joyous retires with 21 wins from 33 starts, eight at Group One level, and prize money of more than $4.5 million.

Gai Waterhouse has appealed against a $5000 fine for not reporting treatment given to the mare on race eve for heat in her neck.

She has denied there was any issue that would affect the mare's performance and More Joyous was passed fit to race by Singleton's vet.