If you want to keep the streets clean, charging by weight is delf-defeating when dealing with a fickle public. Either you’re going to clean up the mess or not - after all, they have paid for the service. There will be some unfairness, but no more than if I overload the dustbin one week (clobbered with excess charge) then go on holiday for the next fortnight and leave it empty (no rebate).

Instead of sending kids on politically motivated trips to the Holocaust graves in Germany, every school should arrange a visit to the recycling process centre and see how difficult it is to sort their rubbish. Me, I peel the labels of banana skins before putting them in the council composting bin. It might help to keep the rates down. And if a job’s worth doing…

I don’t particularly personally favour trying to impose penalties for heavy bins, partly for the reasons you describe and partly because without, say, lockable bins it’s far too easy for those of us with half-empty bins to find ourselves paying for others’ waste that’s been added to our bins. We get people dumping their rubbish in our bin sometimes anyway when our local authority doesn’t even charge by weight. (So it doesn’t matter, obviously - I’m not one of these people who gets very precious about the violation of his bin, or indeed its internal cleanliness or odour…)

But incentives based on bin contents are equally fraught with difficulties and I think Boris is just walking into a minefield here - and it’s a completely stupid minefield to walk into anyway when the Mayor has no powers over recycling anyway. Why bring trouble on yourself over something you can’t really achieve anyway?