William Roache is not guilty. Neither is his prosecutor

Reputation is a fragile commodity. If things had turned out differently, it's a safe bet that Nazir Afzal would be reading admiring profiles of himself this weekend. Afzal is the chief crown prosecutor for north-west England and the man who decided to charge the actor, William Roache, with "historic" sex offences. Not so long ago, Afzal was being hailed for his tenacity in going after the British-Asian men who groomed under-age girls for sex in Rochdale; he also secured "guilty" verdicts against the parents of 17-year-old Shafilea Ahmed, who murdered their daughter nine years earlier. Now Afzal stands accused of leading a "celebrity witch-hunt" against elderly actors, DJs and television presenters.

Roache's statement after his acquittal was dignified but his supporters were angry. They demanded to know why the case was ever brought, claiming that the actor was a victim of the "hysteria" created by revelations about Jimmy Savile. It's a curious conclusion to draw from a "not guilty" verdict; there are courtrooms where the conviction rate is 100 per cent but they tend to be in totalitarian states. In serious criminal cases in England and Wales, the rate is around 82 per cent, and I would be seriously worried if every defendant were to be found guilty.

Talk of "witch-hunts" conceals an inconvenient fact: men charged with rape stand a better chance of walking free than other defendants. The conviction rate in rape trials – 63 per cent in 2102/13 – is quite a lot lower. Prosecutors are taking a bigger risk when they bring rape cases to court, especially when the alleged offences happened decades ago, leaving no forensic evidence. Afzal took the decision to charge the veteran broadcaster Stuart Hall, who still awaits trial on charges of rape and indecent assault. Other "historic" cases have yet to reach an outcome: the trial of the former Radio 1 DJ Dave Lee Travis on 13 counts of indecent assault and one of sexual assault is drawing to a close, while the entertainer Rolf Harris is due in court in April. He has pleaded "not guilty" to 12 counts of indecent assault.

Roache's acquittal follows the "not guilty" verdict in the trial of another member of the Coronation Street cast, Michael Le Vell, who was charged with child abuse. Both outcomes have been greeted as though they represent egregious miscarriages of justice, when they might simply offer insights into the special difficulties attendant on trying famous defendants; on Friday, the judge in the Travis trial warned jurors not to be influenced by verdicts in the Roache case.

If the actor had been found guilty, the papers would be full of articles about his claim to have slept with 1,000 women and his sleazy nickname ("Cock Roache"). Instead, a principled prosecutor has been traduced for doing his job: the accusers in this case had a right to have their allegations tested in court, just as much as the young women who accused nine British-Asian men in Rochdale.

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