The first half saw plenty of good entertaining midfield football without either side creating much in front of goal, but the second half was an entirely different story.
In the 49th minute Swindon’s Alan Sheehan was brought down inside the box by Stephen Purches and Billy Paynter stepped up to beat Jamie Jones from the penalty spot.
Austin – who was playing non league football just two months ago – was only inches wide with a shot before Orient equalised when Gordon Greer’s heavy challenge was penalised and Sean Thornton hit a 30-yard free-kick which deceived David Lucas in the Swindon goal.
In the 75th minute Austin restored Swindon’s lead when he deflected Simon Ferry’s shot past Jones.
He scored again in the 84th minute from close range before Orient defender Tamika Mkandawire was sent off for a professional foul and in the second minute of injury time Thornton scored again with a 30-yard shot.