And that’s just the stuff we can see. As our friends at Mogden will testify, there are even more revolting things happening underground. In this pampered and hygiene-obsessed age, loo paper is no longer considered sufficient for the job of wiping our delicate bottoms. More and more people use wet wipes instead, and then (because they think it disgusting to put soiled wipes in the bin), flush them away.

But most wet wipes don’t biodegrade (and even the ones that claim they do take much longer to fall apart than ordinary loo roll), so they get stuck in the sewers. Oil, grease and food products then build up around them, creating solid “fatbergs” like the 15 tonne blockage discovered under the streets of Kingston, Surrey, in 2013. This monster caused such a build-up of raw sewage in the system that it nearly blew the lids off the local manholes.

There is an uncannily direct contrast between the appeal of the wet wipe (personal and domestic cleanliness) and its effect on the wider world (utter squalor). It’s a modern morality tale: the more selfish and squeamish we become, the greater our chances of being covered in an explosion of our own excrement.