Quite right too. The only acceptable use of email in that circumstance is an auto-responder stating:
"I am on annual leave and will be back on <Day/Month/Year>. If the matter is urgent, please contact <name>".
If the company has made no alternative staffing arrangements then <name> is your line manager.
The only people who should be working when on "annual leave" are the self-employed and only at their own discretion (since the concept of annual leave doesn't really exist for contractors/freelancers and those not "employed" in the normal sense).
Obviously this does not apply in the Land of the Free where your Freedom to be worked to death as a corporate wage slave is feverishly protected.
It's a fair point that reporting standards may vary though. Some forces may be more focussed on serious misconduct (illegal access of protected data for personal gain/criminal use, etc) and less concerned about someone using their @police email for personal use (though I never bloody understand that either - drives me up the wall getting personal emails from people @nhs.gov.uk. Why? Just get a free personal account FFS).