Perth filly Arcadia Queen is the toast of the west after a brilliant victory in the Kingston Town Classic, the final Australian Group One race of the year.

The three-year-old, raced by Western Australia's biggest owner Bob Peters and trained by Grant and Alana Williams, beat a field of older, more experienced horses to win the 1800m-feature at Ascot.

Her win also justified William Pike's commitment to get down to 50kg after he chose to ride her over stablemate Galaxy Star who ran third with Material Man splitting the pair.

Sent out the $2.25 favourite, Arcadia Queen had 4-1/2 lengths on Material Man ($6.50) with Galaxy Star ($5.50) who Pike rode to win the Group One Railway Stakes, a long neck third.

"I was checking over my shoulder because I got there so easily, so early," Pike told Sky Thoroughbred Central.

"I thought I would follow Material Man but I ended up in front of him she jumped so well.

"She is a beautiful horse.

"My first instinct was to ride her but you can't dismiss the other girl and the choice was not by a clear margin."

Peters has won the race five times and said Arcadia Queen's win was the best he had seen but he stopped short of calling her the best he has owned.

"I thought she was our best filly and she lived up to that," he said.

He will now consider eastern states options for Arcadia Queen who will have a break after winning five of her six starts in her first preparation which began in September.

Prompted by talk of the new $7.5 million Golden Eagle for four-year-olds in Sydney next spring, Peters had one reason to lean to NSW over Victoria.

"You can use Regumate in New South Wales. That makes it easier than going to Victoria," he said.

Controversy surrounds Regumate which controls the breeding cycles of fillies and mares with Racing NSW introducing a rule allowing its ongoing use after minute traces of steroids were found in swabs,

Grant Williams said any decision on where Arcadia Queen raced in the autumn and spring would be left up to Peters.