People have been asking how I did this and I should probably have explained when I first posted it, so I’m editing the post now to add a description.
In order to achieve an effect like this one simply needs to use a zoom lens and make a long exposure, zooming out during the time the shutter is open. In this case I used a five second exposure and zoomed in tightly on the green spire. After tripping the shutter I counted four seconds and then zoomed out during the last second. As the lights below were much brighter than the spire, the result is that there is little or no visible light from the spire captured while zooming, leaving the top of the frame nice and dark and getting light trails below.