In the US where driving is done on the right side of the road, it translates into an unspoken “rule” of traffic flow for pedestrian circulation. For example long narrow hallways in office buildings it’s common courtesy to stick to the right when passing someone going the opposite direction. Same thing for a public sidewalk or bike trail, stick to the right.
So in the UK where driving is done on the left, do they stick to the “left” in hallways, on sidewalks, etc?
We’ve definitely done this one before. And there’s no clear answer. Some people will say yes, we always stick to the left, haven’t you noticed? I dispute this, and I don’t think there is any clear unwritten rule, either side is fine. Some individuals may always opt for one side, in which case there can be confirmation bias - because the oncomers they encounter will end up moving to their left as a result.
On escalators it’s common to be instructed to stand on the right.
However, on the escalators on the London Underground, you travel in the escalator on the left, so that when people step off the escalator they tend to keep on walking on the left (from my limited experience).
Very true.
Whereas those standing on the right continue to stand on the right? 
It is normal Underground practice to “keep left” but there are some layouts where this is not possible, for example the passageway at Victoria station from the main booking hall to the Circle/District Line platforms where the signs advise you to “keep right”.