Just going to throw these into the mix as well. Along the embankment, about halfway between the 2 bridges there is the RAF memorial. It doesn't appear to be visible in the LMI6 pic, well, doesn't appear to be lit. It does appear to be quite prominent in other admitedly high res pics, but it does appear that it should (?) be visible in Q's pic.
This maybe a complete red herring as it possible that the lights are turned off at a certain time. Just seemed a bit odd.