It’s been a while since I’ve been caught out, but I’ve just had a £60 Congestion fine passed onto me by the Jaguar press office. It is very easy to forget to pay, especially when you drive into central London for the evening and don’t return home until after midnight. 

Indeed, the forgetfulness of drivers, and the ease of straying into the C-Charge zone, was one of the only things keeping the C-Charge alive for its first few years of existence. The costs of administering the scheme was far higher than predicted, but so was the level of fines for non-payment, so the scheme staggered on for two years before the charge was hiked by 60 per cent, from £5 to £8.

Then-Mayor Ken Livingstone claimed that the hike would raise another £45m per year, to be spent on buses and the underground. The Mayor was, however, being economical with the actualité. 

I’m no great accountant, but I looked at the C-Charge accounts, and executed a bit of basic GCSE-level maths, to make an alarming discovery. The admin costs of the scheme were £4.75 per car, per day. Which meant that the C-Charge was making just 25p per vehicle. The rest of the profit was made up of fine income. No wonder the charge was hiked by 60 per cent. 

I wrote to the Financial Times (who published my letter after asking me to show how I’d worked the figures out) pointing out the truth behind the ‘success’ of the C-Charge. My letter resulted in an angry - but rather blustering - response from Transport for London. 

Part of the reason for the high cost of running the C-Charge scheme is the fact that the overhead ANPR (Automatic Number Plate Recognition)  cameras are not accurate enough to send out automatic fines. Of course, a single misread letter or number by the computer programme and the resultant fine is sent to the wrong driver. 

As I understand it, the pictures of the number plates belonging to vehicles that have not paid, have to be downloaded, visually checked and typed into a database by an expensive team of humans.  

In 2007 London’s C-Charge was, controversially, extended westwards into affluent Kensington and Chelsea, though it’s widely accepted the move was purely political. Current Mayor Boris Johnson has recently removed it. More seriously for the C-Charge’s financial health, Johnson has also introduced an automatic payment system, which should remove the need to ever again be fined £60 or £120 for forgetting to pay. 

With fine income heading southwards, the financial argument for the C-Charge will also be heading southwards. What enthusiasts for so-called ‘Green’ taxes always forget is that a green tax is supposed to change behaviour, not provide an income stream. 

Surely, then, if the C-Charge actually starts to lose money, then it should be considered a great success, because drivers have been convinced to stay away from the centre of the capital.  

Environmentalists need to make their collective minds up. Do they want empty streets or stacks of cash? Because, as the C-Charge is about to demonstrate, with ‘green’ taxes, you can’t have both.