London’s five billion pound Super Sewer is now fully connected and promises a cleaner, healthier River Thames. The 150-year-old sewer network has struggled to cope with the twin challenges of an increase in the population it serves in the capital (from four million people when it was built to over nine million today) together with climate change. With rainfall overwhelming the system, it sometimes discharges into the Thames. With the Super Sewer fully connected, 95% of those spills are stopped.

I’m looking out the window to the street below. One of those annoying yappy dogs is dragging its owner on an exceptionally long leash. Everything about it bugs me, including its colouring (which, by the way, matches the oblivious owner’s hair). `That dog has a brown head and a black body,’ I hear a voice say. I jump and turn but see no one. But I know who is speaking.