Photographs show different viewpoints, dates and conditions. They do not establish current access to a particular route. Every image is credited below.
London is more rewarding when a day has a thread: a river, a period of history, a collection or a neighbourhood. Major sights can then become stops in a wider walk rather than isolated reservations. Public spaces and ordinary streets help connect the city's grand institutions with the life around them.
Book the few things that really require a time slot. Keep the rest of each day in the same general area and leave time to explore between them.