How about a friendly amendment aka hijack?
We will arrive Tuesday late morning and depart Thursday AM, so have two nights, one and half days. Two adults who have been previously, one 18yo on her first visit. Priority is giving her a quick taste of London. Staying in the city near Blackfriar's bridge.
What would you suggest?

My favorite sites in London are:

Kensington Palace - I especially liked the dress displays, and having coffee in the Orangerie (is that two sites?)
Apsley House
Spencer House

Seamus, I think that you will get more response to your particular question if you start your own new thread and pose your question there.