Exactly, they keep doing this time and time again when there is a bit of a media frenzy and steam in thinking they can arrest anybody without doing any homework.
Not strictly true. The police have to run the case by the CPS before they can charge anybody. The CPS review all the facts and they base any prosecution on a 60% probability of securing a conviction. The CPS are all trained lawyers and it is they, not the Police who authorise the charging of suspects.
It's all very well steaming in but if the cops don't do their homework then the CPS will not authorise proceedings.