Don't you believe it! Of course there would have been. There was a huge clamour for the re-opening of the Hanratty case, for the verdict to be overturned and a posthumous pardon granted, blah, blah, blah. - and then forensic techniques, not available at the time of his trial and conviction proved conclusively that he was guilty as hell. Whoops!And, as far as miscarriages of justice leading to erroneous execution is concerned, I also appreciate (but do not agree with) the stance of the former lord chief justice who refused to consider the Guildford 4 and Maguire 7 appeals on the grounds that if they had succeed it would have brought British justice into disrepute. And had we hanged them at the time nobody would be attempting to overturn the convictions.
.........and then there were the idiots that proclaimed George Davis* was innocent, although he was no more innocent than the earth is flat! So, the idea that nobody would be campaigning for the Guidford 4 and the Birmingham bombers to get posthumous pardons is delusional.
*Yes, I know he wasn't hanged, but the point is that many misguided twats campaigned to 'prove' black was in fact white, and there always will be.