Imagine spending three weeks sluicing away 15 tonnes of congealed fat, wet wipes and ‘sanitary items’ from a London sewer. A Herculean task if there ever was one – give me the Aegean stables full of sweet smelling horse manure any day.

Most right thinking people’s reaction to the ‘fatberg’ story would be “Urgh!”, but us circular economy freaks’ initial response is “what a waste!” All that good bio-sourced hydrocarbon could be used as an eco-friendly fuel rather than soaking up more energy to shift and treat. And it seems that London Mayor Boris Johnson, despite his somewhat singular attitude to climate change science, is with us – he wants to use the cooking fat being dumped in London’s sewers to power buses.

The circular economy requires a complete shift in mindset. If you have an acidic waste, say, then the conventional wisdom is you must treat it with an alkali to make it safe. By contrast, the circular economist thinks “What a waste of acid and alkali – what can I use the acid for?”

One of my favourite sayings is “waste is a verb, not a noun.” As soon as you start making that mental shift, all sorts of possibilities start opening up. These are starting to make an impact on the economy. For example, one of my clients tells me that you cannot buy virgin glycerin in bulk anymore as the market is now dominated by glycerin sourced as a byproduct of biodiesel – a classic industrial symbiosis.

But the fatberg shows we still have a long way to go before we start harnessing all the wasted resources in our economy.