Blake Shinn thought he had received a head start while Tye Angland figured he must have mistimed the jump when the gates opened for the third race at Warwick Farm on Wednesday.

Their confusion was quickly allayed when the warning lights and siren signalled a false start to the All Too Hard @ Vinery Plate, a rare occurrence at a Sydney metropolitan racetrack.

"I'm not sure about the other gates but I think my gate was the first to open," said Shinn who rode eventual winner Kimberley Star.

Angland was aboard Hillary Step and said there appeared to be a longer-than-usual delay between the starter hitting the button and the gates opening.

"I thought my timing was wrong," he said.

Jockeys of all 12 runners were able to restrain their mounts quickly and every horse was passed fit to start a second time around.

That was especially good news for Tulloch Lodge which produced Kimberley Star for an overdue win.

"It's a pity they all had to pull up and go back because that was the best she has jumped out of the gates the first time," Gai Waterhouse's stable representative Mark Newnham said.

Stewards opened an inquiry into the incident and took evidence from several riders along with racing officials including starter Dale Jeffs.

Jeffs said he felt the gates opened haphazardly and instructed a false start to be implemented.

"There was definitely a time lag between me pressing the button and those gates opening," Jeffs said.

Presiding steward Greg Rudolph said replays showed the gates did open simultaneously but there was little doubt something went awry at the start.

Rudolph was adamant Jeffs made the right call to declare a false start.

"The decision was reasonable in the circumstances, given the video and evidence from the jockeys shows an anticipation that the gates should open and they didn't," Rudolph said.

Stewards were unable to find an explanation for the incident but ordered the gates be tested prior to the next Warwick Farm meeting.

Kimberley Star's victory formed part of a winning treble for Shinn who has moved into second on the Sydney jockeys' premiership.

In an exciting three-way battle, Shinn is four wins behind James McDonald, who is currently in England on a summer riding stint for Godolphin, and half a victory ahead of Hugh Bowman who booted home one winner at Wednesday's meeting.