It is hard to think about Christmas in the ­middle of a summer heatwave, but retailers in the northern hemisphere are shivering. A cocktail of circumstances — some expected, some not — have knocked global liner logistics for six.

New Covid-19 lockdowns in southern China and mounting port congestion there and in western Europe have upset schedules.

That is on top of box shortages, continuing Covid-­related crew-change difficulties and the fallout from Evergreen Marine’s Suez Canal blockage in March.