Rachel McLean

– Thrillers That Make You Think

What Would Happen If the Thames Barrier Failed?

The long and short of it is that it would be a disaster.

If you’ve read Thicker Than Water, you’ll know that it happens six years after London is overcome by floods.

Six years on, we’re transported to a community of refugees from the flood who’ve made their home on the Yorkshire coast.

They’re not all from London: the Evans family (who we’ll get to know well through the course of the book) have walked to Yorkshire from the Somerset levels, and Martin (we’ll get to know him even better) finds that the floods give him the opportunity to flee his abusive father in Norfolk.

But more people in the village come from London than from anywhere else, and that’s for two reasons: population and infrastructure.


London is far and away the largest population centre in the UK: nearly 9 million people live there. A growing proportion of them live within reach of the Thames. According to the Environment Agency, without the Thames Barrier over a million homes would be at risk.

Now, I’m not claiming that London and New Orleans are the same. Much of London is on high ground that wouldn’t be affected. But if the Thames flooded, a lot of people would be without a home. There wouldn’t be any spare homes locally, and those charities, churches and other organisations that took people in would be overwhelmed.

Ten years ago we saw a storm that was similarly destructive: Hurricane Katrina. It breached the levees around New Orleans, leaving over a million people homeless and nearly two thousand dead. And that’s in a city with a population of under 400,000, approximately 4% of the population of Greater London.

Hurricane Victoria is so severe that the Thames barrier is breached. Those more-than-a-million homes are flooded and their inhabitants are left without adequate support.

So where would everyone go? In Underwater, the prequel stories to Thicker Than Water, they head North.


London wouldn’t just be vulnerable because of the density of its population. Its infrastructure, and the part it plays in the infrastructure of the whole country, would amplify things.

The Environment Agency estimates that no less than 51 railway stations, 35 Underground stations, eight power stations, more than 1,000 electricity substations, 400 schools and 16 hospitals would be affected if central London were to flood.

Which begs some questions:

  • With the tube and railways underwater and people panicking (and London’s traffic bad enough as it is), what would happen to the roads? My guess is that they’d grind to a halt.
  • How would all those people seeking to find a new home get around, or out of, the capital?
  • Would anyone be able to resume their day to day life, with schools and offices affected?
  • Given that the Houses of Parliament would flood (and 10 Downing Street), where would Government move to?
  • With all those hospitals out of action, how would those injured in the floods get treatment? And what about all the thousands of people reliant on regular medication to stay healthy or even alive? With no transport, supplies would dry up.
  • With power stations and electricity substations out of action, would the capital be in darkness?

It wouldn’t be good. If I was Jess Dyer, I’d grab my family and start walking away from London. Which is exactly what she does….

I can’t possibly examine all of these issues in one novel, which is why I’m already planning a follow-up which will show the long-term effects of the floods in more detail. I can’t wait to start writing it!

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3 responses to “What Would Happen If the Thames Barrier Failed?”

  1. Horrible disaster to even contemplate (national security too?)- but writers write. Ambitious, but go for it, Rachel! Tom

  2. Avatar Gaz says:

    As a country, we do tend to put all our eggs in one basket and then suspend that basket on a hook held to a wall with blu-tac. Let’s hope for the best, but fear the best, seems to be our motto. We need to start building a “London 2”, somewhere more inland and slightly more central to the whole UK. Not a new city, but develop an existing city. It would be a 100 year project, but I think it needs to start happening.

    • Avatar Rachel McCollin says:

      Interesting solution, Gaz! Maybe we can move the capital to somewhere that’s already inland – maybe my home town of Birmingham? Or maybe not, I quite like Brum as it is.

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