I saw a high-profile case where this happened today and wondered about it.
I understand there probably will (and probably should) be some leeway in this, but if one was arrested for breach of the peace, which under English common law does not require an arrest warrant, could that then be dropped and replaced with another charge that would've required an arrest warrant?
Or, if there is some leeway to do this, can it be challenged? It seems to be, shall we say, convenient that the police are using a power that is given for situations of immediate need in a way that could be said to circumvent the system somewhat.
I've had another look through the Police and Criminal Evidence Act 1984 (PACE) and through the codes of practice for PACE but haven't found anything referring to this.