However, each year large swaths of London still have a 1-in-1000 (0.1%) or 1-in-100 (1%) chance of flooding. The map below, from the UK's Environment Agency, shows the risk of flooding across London.

THE Thames Barrier has closed again this morning as flooding continues to the west of London - with Greater London at "medium risk" and no end to the rain in sight.

Of course, it's just a simulation; the barrier closed Thursday right in time for a monster tempest that forecasters said could deliver the U.K.'s biggest storm surge in 60 years.

But the Thames Barrier, which was built in 1982, protects the city. With its alien-looking metal domes perched above the water, the barrier has become an iconic piece of London’s infrastructure.

As the Thames winds its way to Essex, it broadens and the rock beneath it softens, making tunnelling difficult. Since big ships still visit docks in the east, any new bridge would have to be ...