A minimal reduction today, which probably falls under the heading of experimental error, or looking at the scale from the wrong angle, or something.
This is a trolleybus. I remember these from when I was a very young me in Cardiff several years ago.
Shutter speed: 1/170s
Focal length: 20.1mm
Taken: 3 January, 2015
 Not this model though. I seem to recall Routemaster-style open platforms at the rear rather than doors
 For an arbitrarily large value of “several”