Well, compressed air, to be strictly accurate.

This morning I noticed that my little car had low pressure in one of the tyres, so I stopped at a local garage to check all four of them – only to discover that their air compressor is now coin operated.

Stuff that. I have been giving them fifty quid a week for diesel for the last three years. I am not paying them 20p for ten minutes of compressed air.

So I drove on to the next garage, and then another one, and another… six garages, all now sporting brand new coin operated air compressors on their forecourts.

Why? A quick search on the Electric Internet reveals that coin operated air compressors cost about £10,000 more than free ones. Which means that in order to pay for themselves, they need to be used fifty thousand times. Get your calculator out – that would take a year of constant use, 24 hours per day, by paying customers.

And that’s not going to happen in a place like York: first because there are only 75,000 cars in the entire city, and we know that there are at least six places trying to charge customers to check their tyres; and second because Tesco are selling electric tyre pumps that run off your car’s power point for £4 each.