This is true, there's no specific way to address a policeman in England, just use normal polite speech... some people can't even manage this, although of course being blatantly disrespectful might land you on the wrong side of the law even if you were on the right side to start with! I remember one time when I accidentally swore in front of a policewoman... although actually she might have just been a Community Support Officer. CSOs are basically civilians dressed up to look a bit like police officers. They don't have any real powers, but I suppose the advantage is they're cheaper than actually hiring more police.
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