At about 4ish pm near Westminster Hall, you will find a rush of people. Tourists here for this and that, others rushing between buildings for work and heading home. During most of the day, a lot of the hotspots of London are tourist spots. This, of course, has the downside of a) things being expensive and b) places being packed. During the day we admittedly participated in some of the tourist activities, such as touring Parliment (which was actually very awesome); the ability to do so was actually great luck since Parliment happens to be in recess while we are here.
Later in the evening, you will see the city taken back. More of the locals come out and even the usually busy London Eye and Hungerford Bridge area seem to clear up from the congestion of the common large groups with matching hats.
At night we went out to that area around the London Eye to take some photos and get frozen yogurt from the double-decker bus (which ended up also being a great photo location). It was a very different experience to be able to walk through those areas with so few people there, it made the city seem quite and actually a bit smaller. There weren’t cars honking and ripping by, even the London Eye stood still for a time. All you could hear was the breeze blowing by.