Grant Williams, trainer of Group 2 $400,000 Perth Cup winner Western Jewel, has rewarded the faith of Western Australia's leading owners, Bob and Sandra Peters, who selected him from relative thoroughbred obscurity to be their key trainer almost two years ago.

Before that Williams was Western Australia's leading harness racing trainer and driver. He continues to hold a dual licence, and regularly trains and drives winners at Gloucester Park.

Western Jewel, a daughter of the 1994 Melbourne Cup winner Jeune, produced a brilliant burst from the back of the field to give Williams his first win in the Cup and the Peters' their fourth-they previously had won with Field Officer in 1993, Crown Prosecutor (2005) and Lords Ransom (2010).

The win also was a reward of faith in star apprentice Kyra Yuill, who was unlucky on the mare in last year's Perth Cup, and had been out of form this season.

Williams and his wife, and assistant, Alana, a former leading apprentice under her maiden name Alana Sansom, were given a small contingent of arguably moderate horses to train from the Peters' sizeable team of thoroughbreds in what was probably a test of their talent.

Williams seized upon that small window of opportunity and his success has snowballed to such an extent that the combination of Williams and Peters has had a huge impact on racing in WA in the past 12 months.

The Williams-Peters team cut a swathe through the 2011 WA autumn carnival with outstanding 3YO filly Dreamaway, who won the Group 3 Champion Fillies (1600m), the Listed Ascot 1000 Guineas (1800m) and the Listed Natasha Stakes (2200m) before a brilliant victory in the Group 3 WA Oaks (2400m) and a stunning win over Playing God in the Group 1 WA Derby (2400m) a week later.

Dreamaway was ridden by stable jockey Willie Pike, while Yuill has settled into the position as number two rider.

Until recently, the great form of the autumn hadn't transferred into the new season. Stable star Ranger was luckless at Group 1 level before he was spelled and Lords Ransom showed he was struggling for form that also forced him out of the Perth Cup.

Things took a turn for the better when Yuill snapped out of her form slump with a winning treble at Ascot on December 17, including an upset victory aboard Moonlight Bay for Peters and Williams in the Listed WA St Leger .

Yuill followed up a week later with a near perfect ride on Western Jewel, when the 5YO scored a comprehensive win in the ATA Handicap (2200m) at Ascot on December 24.

It was a performance that indicated the mare was right on target for the Cup and ready to atone for her luckless effort in last year's race, despite drawing barrier 16.

With a confident Yuill riding to instructions, Western Jewel settled near last before looping the field on the corner and unleashing a barnstorming finish to beat God Has Spoken and Senhor Da Gama. Yuill is the first female rider to win the Perth Cup and the third apprentice, joining Pike (Crown Prosecutor in 2005) and Peter Knuckey (Field Officer, 1993).

Williams had four starters in the Cup, all owned by Peters-the others were Pike's mount Tranquility (4^th), Moonlight Bay (7thy, Marco Chui) and Battle Emblem (8^th, Paul Harvey).

The disappointment of the race was the $4.20 favourite Kincaple, who settled back and finished 12^th. Jockey Dwayne Dunn reported that Kincaple was sore.

It was a red -letter day for WA's harness fraternity with former leading harness trainer-driver Justin Warwick-another dual-licensed trainer that is really starting to make an impact upon WA's thoroughbred racing-preparing his emerging mare Rosie Rocket to an effortless victory in the Listed $80,000 La Trice Classic, the final leg of the rich WA summer carnival series for mares.

It was a training triumph for Warwick, who in a little over nine months has guided Rosie Rocket from winning a provincial maiden to be a two-time Stakes winner.