As far as Kensington & Chelsea go. They have put M/C resident permit holder bays in with ground anchors. The permit costs £30 a year. You can get a £15 discount if you have some form of advanced training - like Bikesafe. A combined permit which allows you to park in any resident parking space and the M/C permit bays costs £80. (my car costs £112)
There are still the free bays (at the moment) but obviously they get full up with riders from out of the borough. Even though the council has increased the number and size of some of the free bays. My main complaint is with the Pizza delivery scooters who clog up the free bays during the day. Leaving no space for non commerical riders.