The sudden appearance at high streets, malls and retail parks of masks en masse rather than among a minority of consumers – in my experience, at least – renders visible that unnerving reality.

The implications for retailers are not yet clear. Will masks build consumer confidence or shake it? Either way, they represent a flashing light that signals the need for vigilance.

That vigilance comes into play too as far as people’s willingness to travel to work goes. Travel hubs such as railway stations and the big city centres they normally funnel commuters into still lie pretty much deserted – a heavy weight to bear for the many retailers that rely on office and other urban workers for some of their most lucrative trade.