A “catastrophic breach” of London’s river defences would mean floods could hit Parliament, Downing Street and MI5’s headquarters within 30 minutes, Westminster City Council has warned.
A study has mapped the likely course of flood waters in the capital in the “extremely small” chance that the Thames’ defences failed.
Councillors said that the capital is likely to become more vulnerable to flooding because of rising sea levels and heavy rainstorms brought on by climate change, but overall was well protected by the Thames Barrier and Embankment Wall.
Thousands of homes and businesses in Westminster and Pimlico, as well as Scotland Yard and parts of Whitehall, could also be at risk of flooding, according to the study.
The council believes that the chances of floodwater overwhelming riverside landmarks with up to two metres of water in a matter of minutes are extremly small.
The Thames Barrier would have to fail, with a one-in-200-year tidal flood event and several breaches of the Embankment’s defences.