This Environment Agency picture shows the effects that the largest tidal surge in 60 years would have had on London if the Thames Barrier hadn't been closed.
Thousands of people were evacuated from their homes down the east coast of the country during storms last week.
But the 520 metre barrier saved London from the worst effects when it was shut on Thursday and Friday.
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A lamp in the tower which houses Big Ben is to be switched off for the first time in more than 70 years.
Sir Bruce entertained audiences for more than seven decades.
Work in the tower will also pause over the bank holiday weekend.