The older 870 Police model wasn't marked as such. They usually just had standard Wingmaster markings.
I'm not sure just when Remington started adding the Police marking, but it was possibly at the same time they started marking 3" Magnum guns as Magnums.
One good indication of an earlier Police gun, is the more satin blue-black finish, and the short Police forearm.
My point was, a good number of people are advertising Express guns as "Police Models".
I've recently seen the Express HD, Magnum Marine, and the new OD Green guns all described as "Police" guns..........They AREN'T.