This isn't an Official Police, its a Colt Officer's Model, which was Colt's target revolver.
Basically, its a better built, better finished target version of the OP.
The Officer's Model was made from the early 1900's to 1969 in several different versions.
The exact model depends on the serial number. The First Model was made from 1904 to 1908.
The Second Model was made from 1913 to 1923.
The Third Model was made from 1927 to 1949.
After the war, Cold made the Officer's Model Special and the Officer's Model Match.
To find your year of manufacture, check this web site: