I would expect outages when talking to a server on the other side of the country, and an outage preventing supermarket customers from checking out or supermarket staff from usefully restocking shelves would be a very expensive mistake.

A good system here will be distributed.

That being said, two servers (for redundancy) physically located at each branch ought to do the trick. Tesco has a bit over 5000 branches [0], so that’s 10k of the 40k VMWare seats right there. Throw in some extra seats so storage and compute can be separated at each location (maybe unnecessary but comes with some benefits) and so that there is still redundancy while a server or two at a site is being re-imaged and 40k seems about in the right ballpark even for a fairly lean implementation.

And, sure, all those on-site servers might be relatively inexpensive industrial units designed to tolerate a toasty, dusty, and occasionally damp closet that looks nothing like a tidy datacenter, but it still makes sense to run something like VMWare on them.

[0] https://www.tescoplc.com/investors/reports-results-and-prese...