Are you sure? Usually the official naming is when charges are brought (before that they give age, sex and perhaps location) as soemtimes those arrested are completely exonerated. If course information about the case already in the public domain means it's someiptimes easy to work out who the detainees must be (recent exampe: Philpott parents).
In is case there is also a public interest because of the pre-existing manhunt, and also he turned himself in rather than being apprehended, and I don't know if either of ise factors make a difference.
Miss M The police did not name the Bristol landlord. It was the media who did that.
How would they know? Well, it wasn't difficult to work out and they were hanging around the place all the time and would have seen him leave anyway.
Meanwhile the BBC are reporting that the man arrested on suspicion of conspiracy to commit murder re the two GMP officers has been released without charge. Not sure if it was the police who named him or not.
It will be a long time before Cregan is asked to enter a plea, that process comes a long way down the line. Makes no odds if he admits anything now or not. Look at the bloke charged with the murder of Sian O'Callaghan. He showed them where her body was AND volunteered the burial site of another victim that no one knew about .... and he is pleading Not Guilty.