Really, that couple shouldn't have been named. The police said that the arrest was 'lawful'. Assuming that those two did nothing wrong and weren't involved in any way, there was no evidence at all against them (an accusation is not evidence, however many people say the same thing), so it was false imprisonment. I hope that they get good compensation.
A far worse case was when that garden designer in Bristol was murdered. Her landlord was charged and named - he didn't do it, but his reputation was ruined.
Yes, absence of evidence is not evidence of absence, but evidence is not proof. In the absence of guilt there is no evidence at all, just incompetence and stupidity.