This from Wiki: //The standard of proof is that the unlawful killing must be beyond reasonable doubt. If this standard is not met, a verdict of accidental death or death by misadventure on the balance of probabilities may be returned.//
I don’t know much about this, and I understand the accusations that the police lied, but bearing in mind that according to Mikey’s OP //The Jurors answered yes to the question about whether any police error caused or contributed to a dangerous situation//, if the police are indeed wholly culpable, I’m concerned by the word “contributed”. It appears that this terrible tragedy resulted from several contributing factors; the actions of the police, the behaviour of some of the fans, and the safety issues within the ground. Therefore, I don’t see how the police can be deemed, without reasonable doubt, to have been solely responsible, hence the ruling of 'Unlawful Killing' against the police alone appears to be questionable.