Apparently, the story will include some sort of alternate history where the Nazis successfully invaded Britain and ended up using Churchill’s home as their base of operations.
The film shot scenes there during production, including the swastika banners that we see here.
The structure is the home of Winston Churchill.
While the context of this image is still mostly a mystery because the Transformers: The Last Knight connection to World War II is still hazy, we do know one thing about what we see here and that’s the building Bumblebee is standing in front of.