Eyewitness statements aren't reliable (hell, I've given an eyewitness description that wasn't that reliable, judging by the reaction of the police officer who had just taken a statement from somebody else), but I'd see it quite hard for a court in a pre-DNA testing era not to have convicted when a reasonably certain and consistent testimony from a rape victim is supported by the supposed forensic experts at the time, especially not if the chief argument for the defence was a weak alibi offered by the accused's mother.

Though since they've had DNA techniques sufficient to overturn the expert witness evidence for rather a long time now it's surprising it took this long to overturn.