Your account is not consistent with the photos which show you parked in the first bay of the 'police only' parking place, which is the first parking place in the road. Your nearest traffic sign was the black on yellow 'no stopping' sign. The resident's bay sign was in a different bay completely. Your argument as currently structured won't win IMO.
A 'police only' sign, whether no waiting or no stopping, is a permitted variant of the 'taxis only' sign. ALL other elements of a 'taxis only' bay remain i.e. the broad yellow line(if no stopping, as here) and yellow road markings to replace normal white when the bay is reserved 24/7, as here. As you now know, the road marking 'POLICE..' is optional.
In your photos, I can see the broad line and the road markings, but neither appears to be yellow. Look at GSV and you will see the Sept. 2009 version of the markings, all pristine yellow.
Today's pale, literally, in comparison.