Are you logged on to Klarna, Clearpay, Laybuy or Zilch for your Black Friday shopping binge — or are you an old-timer like me who still uses traditional credit cards and even sometimes tries to pay for purchases in cash? If those four brand names meant nothing to you, you are yet to join the millions of UK shoppers who have discovered ‘buy now pay later’ (BNPL) apps that offer, with a couple of simple checkout clicks, payment for fashion and beauty purchases, and even groceries, in a series of interest-free instalments.