We don't know how often every frontline police officer carries a gun, largely because these orders are not usually announced and because police headquarters does not keep records of this sort. Why not?
Its a good question. Whether to arm police is an important policy decision and one which requires the highest level of public scrutiny. A refusal to keep records (or the keeping of records in a haphazard, distributed fashion so they cannot be recovered) frustrates this scrutiny. Which is, I suspect, the point. But while it is convenient for the police, it does not appear consistent with the duty under the Public Records Act for public offices (explicitly including the police) to "create and maintain full and accurate records of its affairs, in accordance with normal, prudent business practice" is left as an exercise for the reader. Failing to obey this requirement is a criminal offence. So maybe someone should lodge a criminal complaint and see whether the police actually obey the law, or place themselves above it?