Dennis Lillee said in 2007 that he was one of the fielders that day (at mid-on I think he said) who were meant to begin walking in as the bowler made his run-up, and for the ball in question, he failed to do so, so was outside the circle when the ball was delivered. This would mean (given the fielding restrictions in effect) the ball was a no-ball. I have done a brief search for a source for this, but I recall seeing it in an interview in 2007, so I presume there is a written or video source out there somewhere.