Stalls one to four opened half a second before the others in the 10-furlong race won by the 16-1 shot Jubilee Scholar (drawn 12), who beat Grooms Gold (3) and Temptress (5).
Most racegoers believed the race would be declared void, but the stewards confirmed the result. This brought an eruption of abuse from the crowd.
Hugh Collingridge, trainer of fifth-placed Captain's Day (10), said: "I can't believe what I'm hearing. Those four got a two to three-lengths advantage on the rest."