The 19-year-old debutant appeared to have been just caught short of his ground on six when a stumping decision was reviewed to third umpire Marais Erasmus. The Zimbabwean official saw things differently, reprieving Agar to go on and make 98 - a world-record Test score for a number 11.
Erasmus was again under the spotlight after he overturned Aleem Dar's on-field decision not to give out Trott lbw for a first-ball duck. Replays seem to suggest an inside edge but, with the Hot Spot technology absent, Marais opted to send Trott on his way.
Australia were this time left incensed as Broad stood his ground after his thick edge went off wicketkeeper Brad Haddin's gloves and to Michael Clarke at slip. Dar - like Broad - was unmoved, though, and with Australia having used up all their challenges the England man remained.
Shane Watson and Michael Clarke
Australia's two top batsmen were both given out on review, ironically both to Broad, though neither seemed entirely happy. Watson was given lbw but decided to review what looked a marginal call. He was left disappointed when Hawkeye showed the ball to be clipping leg stump and it went with the on-field decision. Clarke was then given out caught behind but did not believe he had made contact with the ball and sent it upstairs. The tiniest of nicks seemed to show up on the infra-red and he was on his way back shaking his head.
It was almost fitting for the wicket that decided the Test and gave England a famous win involve a referral. England hardly seemed completely confident - with neither James Anderson nor wicketkeeper Matt Prior appearing too convinced of a slight inside edge. Captain Alastair Cook opted to gamble and another feathered nick gave England the result.