For a discussion about the frequently incorrect addition of foot=no through a StreetComplete quest which is now disabled in the UK, see:
https://community.openstreetmap.org/t/poll-should-streetcomplete-disable-the-are-pedestrians-forbidden-to-walk-on-this-road-without-sidewalk-here-quest-in-the-uk/118387

The fundamental issue here is that access tags in OSM are supposed to represent legal permissions and restrictions. In that context for public highways in the UK:
foot=no requires explicit signage
foot=use_sidepath doesn't exist

Having said all that, many thanks for the separate sidewalks you added on some of the main roads in the City of London. Those will be helpful to people like me who use OSM-derived pedestrian routing applications.