Some of us are able to walk in high heels and some of us are stompers who can't. I fall in to the latter category. I can do taxi to table in high heels. I can do a party where no walking is required and I can dance like a mad thing in heels and then I drop. And I have to walk, walk to get train, tube, bus or just plain walk. Of course the trouble with flats is they prevent one from longer length garments and in London I do find floor grazing clothes an issue. It makes me feel ill if they are making contact with the pavement.
Boots for walking the streets of London town need to have enough of a heel to allow for a lean line of trouser, skirt or dress and be conducive to the stomp.