Build a hill and they will come. This, at least, is what Westminster council is betting on, having lavished £2m on a temporary mound. Rearing up at the western end of Oxford Street as a faceted green shell, looking like a landscape from a low-fi video game, the 25-metre high Marble Arch Mound is one of the more unlikely strategies for stimulating our Covid-stricken high streets. “You have to give...