Sir Mark Todd's autumn sojourn to Sydney with Eminent has renewed his enthusiasm for training thoroughbreds and sparked his decision to retire from eventing.

New Zealand's most famous equestrian and a dual Olympic gold medallist, Todd announced on Monday he would not compete in Tokyo next year.

He retired immediately after helping New Zealand win the Nations Cup at the Camphire International Horse Trials in Ireland.

It is the second time Todd has retired to concentrate on racing.

He took up training after the Sydney Olympics in 2000 and prepared NZ Group One winners Bramble Rose and Willy Smith.

He came to Sydney earlier this year with the Eminent who is owned by NZ Bloodstock's Sir Peter Vela.

Eminent, who raced as He's Eminent in Australia, finished second to Avilius in the Group One Ranvet (2000m) before failing in the Queen Elizabeth Stakes won by Winx.

"We had a brilliant time campaigning Eminent in Australia," Todd told NZ Racing Desk.

"I really enjoyed the racing scene over there. We had a high quality horse and he was a bit unlucky in his first run that we struck a wet track.

"Then we had a few things not go quite to plan after that. He didn't show his true worth, but it was a great experience. Hopefully we can have another one good enough to come back some other time.

"Since the beginning of the year, when I started with Eminent I have been thinking about retiring from eventing,.

"A couple of months ago we bought five two-year-olds from the breeze-up sales, so suddenly I had a few more horses.

"I was just finding combining the two was getting a bit difficult. My focus was centring more towards the racing, so I decided to pull the pin on the eventing sooner than I had originally planned."

"It wasn't an easy decision, but now that I have got these racehorses my focus has changed a bit.

"I am looking forward to this next stage."

Vela has shares in the two-year-olds Todd will train from his base in England.

"Sir Peter has backed me again, taking shares in these two-year-olds," he said.

"Terry Henderson of OTI Racing, he has got a share in a couple.

"I have got 10 horses and I have got one arriving today from Henrietta Tavistock, The (Dowager) Duchess of Bedford.

"I trained for her in New Zealand as well, it's good to have another horse for her."