When the British government wanted to test the resiliency of its financial institutions, it commissioned “an afternoon from hell”.

The buildup started on a Monday morning last November. First, there was a failure in the clearing systems used to transfer money between banks after routine systems maintenance. Then, terrorists staged a series of bomb attacks around Britain, causing hundreds of casualties in London and considerable damage to major financial centers. Around the same time, malicious hackers tried their best to break into the banks’ systems.

All in all, ’twas was a bad day.

The disaster recovery simulation was organized by the Tripartite Authorities, a group comprising the Financial Services Authority, the U.K. Treasury Department and the Bank of England. Monitors from KPMG, a consultancy that created the scenario, watched from 14 sites around London as 80 companies and more than 3,000 participants worked to keep their staffs safe and their operations running.

“Resilience benchmarking is prompting companies to examine plans for allowing staff to work at home in the case of an emergency, or plan for transporting workers from London to an alternative site to continue business operations,” said Rob McIvor, head of media relations for the Financial Services Authority. “Also, firms need to focus on staff. We were quite surprised by the small proportion of firms that had immediate access to next-of-kin data.”