Passengers on one side of a plane heading west from London’s Heathrow airport can see Windsor Castle, home to Queen Elizabeth II. On the other — if they know where to look — is a cluster of warehouses that plays an increasingly vital role in the world economy.

The warehouses are owned by US group Equinix, which together with rival Digital Realty dominates the global business of data centres, which host computing and storage systems to enable the delivery of web services. Both are big winners on the stock market this year, as the Covid-19 crisis has shifted more economic activity online. The companies’ combined market value has jumped by a fifth since January, to more than $100bn, while the S&P 500 benchmark of US