We never got off the main floor, except to go into one lower level that had wine and spirits. The main floor was nothing but food and a number of perfume sections. All in all it was crowded and we ate a bit and got out of there.
The main attraction was the National Gallery but we got there well before it opened, so we walked down to Big Ben and the Parliament buildings and 10 Downing Street. Just around the block is the War Room Museum, which was British headquarters during WWII. It's been preserved or restored to very accurate conditions. Several of the various rooms not only have the original furnishings but also have wax figures of officers. The rooms include the sleeping quarters for Churchill and for his wife, as well as the Churchills' kitchen. All in all one comes away with at least a vague sense of what it must have been like, especially when one comes back out, into the fresh air directly across from St James park.
We then walked back to the National Gallery. It's a good museum with some notable works and is laid out well. It left me a little cold but that's perhaps unfair as we spent only 1.5 hours there. Perhaps, too, I've seen one too many Great Art museums. We walked back to the hotel after that, which was quite a long walk, by way of Hyde Park. We saw Speakers Corner which was, as the guidebooks say, much fallen from its glory days. All that were there were six or seven advocates of this or that religion.
The walk back, though long, was pleasant as we got to see a goodly portion of the city. I was struck again by how much of the buildings look to be 18th or 19thc. Along the way we saw a very nice BBC building that looked mid-20thc. Ate in a local restaurant; decent food, nothing memorable. It's 9:30 now and everyone is falling asleep.