'Christmas slots went in five hours': how online supermarket Ocado became a lockdown winner

Ocado's warehouse in Erith, 15 miles east of London on the Thames estuary, is staffed by 1,050 "personal shoppers". Outnumbering them are 1,800 robots the size of small washing machines. You see them by climbing to the top level of the vast warehouse – at 564,000 sq ft, it is more than three times the size of St Peter's in Rome – where a sign tells you that photography is strictly prohibited. The online supermarket is paranoid that rivals will glimpse the technology it believes to be revolutionary. From the viewing platform you can watch these metal cubes endlessly whiz around, moving thousands of plastic crates as if they were playing an enormous game of chess. You occasionally sight bottles of bleach or rosé, packets of noodles and dog biscuits, before they are sent down to a lower level. "I find it quite mesmerising, like robotic ballet," says Mel Smith, CEO of Ocado Retail, the UK arm of the business. "The day I decided I wanted this job was when I went to [the warehouse] and thought, this is absolutely the future."