The RAF Hawk black colour scheme, they can't be seen most of the time low level, why go away from the red white colour. Ok underside could be black.
And the Police dress in black, then put hi viz over the top.
After exhaustive trials a few years ago it was determined that the best paint scheme for conspicuity was...black.
Our 'local' police helicopter is indeed black (or dark blue) with a yellow upper part around the engine nacelles.
TOO