Some workers will have seen the premises beforehand during tests and drills. For others, it will be a completely unfamiliar place. But there are ways to make the transition “seamless” upon arrival, says Morley. For example, Sungard’s Southwark Bridge Road site, which is practically empty on most days, usually keeps two of its three entrances locked. But once a client that rents desk space in the building moves in, one of those entrances can be opened and used as the client’s new reception area. This means that employees can be greeted by the same receptionist who usually greets them at their regular office. One firm even keeps access card swipe machines on location so there is no change in how staff enter and exit the office.

“They literally have machines that they roll out into our reception, just to enable that to happen on a more familiar basis,” explains Morley.

Once inside, staff might find signs posted in the lift explaining what floor and area they should go to, depending on their role. All the equipment and software they need to do their jobs is ready and waiting.

Such backup offices are termed “hot sites” in the industry because they can be used immediately and don’t need to be kitted out or “warmed up” first. “Cold” sites, by contrast, could be as simple as an empty warehouse to which equipment can be shipped during a crisis.

Providing food is often a challenge because no one can predict when backup offices will be in use or to what extent. Morley says his team keeps lists of local food suppliers – cafes and restaurants – on hand for each location. Firms might, for example, pre-order entire buffets for lunch as Sungard’s buildings don’t have canteens.

Pandemics are a very specific kind of crisis, notes Chloe Demrovsky, president and chief executive of Disaster Recovery Institute International. The main threat that firms have been preparing for in recent years has been a major cyber-attack, she says: “Pandemic was kind of sitting on the back burner.”