When history looks back on that strange phenomenon of the fin de siècle known as “business casual”, it may well cite last Monday as the day the movement died.

That was the moment when Vladimir Putin, the outgoing Russian president, and Dmitry Medvedev, his successor, made a surprise appearance in Red Square in Moscow at a rock concert sporting, respectively, zip-up black nylon and black leather jackets and matching zip-up black polo necks.