I returned to the City Hall, a little earlier this time. The light still wasn't great, but I took a quick picture, leaning over a fence whilst hiding the camera!
Later I headed out with Sarah to take a long exposure of cars at night, driving up to the cathedral - but the cathedral doesn't have any lighting, and it didn't work. With the moon so full at the moment, I'm sure it would be possible to get a late moonlit shot, but it feels far too dodgy to be out late. Starting to find Georgetown difficult - looking forward to moving out of the city!