Government agencies and emergency services will attempt to tackle London’s worst-case scenario for a natural disaster on Friday. With the aid of computer screens in a command-and-control centre at a secret central location, dozens of civil servants, policemen and firemen will test contingency plans to respond to flooding across the capital.

While similar exercises have been carried out in recent years to train London’s response teams for a terrorist attack, this is the first to test resilience to the consequences of what the insurance industry has identified as a “world-class risk” – river flooding in the UK.