In what is a solid contender for this year's Darwin Awards for environmental virtue signalling, the City of London has proposed a 15mph speed limit and the closure of some streets at lunchtime as part of a “radical plan” to reduce air pollution, cut traffic, and promote walking.

With more than half a million people commuting into the City of London each day, the authorities have been working to reduce air pollution in the area which contains several of the most polluted spots in the capital, the FT reported quoting Alastair Moss, chair of transport and planning committee at the City of London Corporation, who said the “radical plans” would help Greater London maintain its competitive edge as a business destination. The new 15mph speed limit could go into effect as soon as 2021, pending further approval from the Department for Transport.

It was not immediately clear how or why the artificial ceiling of 15mph would help the environment, especially since the maximum emissions from a car engine peak at a low rate of speed, but we'll leave that to the Darwin Award nominations committee to answer. There is another, more pertinent question: why impose a 15 mps limit when the average traffic speeds in the City of London are already roughly half that due to narrow streets and congestion.

While the number of vehicles driving in London's “Square Mile” has halved in the last 20 years, the corporation aims to further reduce vehicle traffic by 25% by 2030, and by 50% by 2044. “We are working tirelessly to support the 513,000 workers that commute to the Square Mile every day,” said Mr Moss.

The current speed limit in the City is 20mph for roads controlled by the corporation, while some larger thoroughfares managed by Transport for London, such as Blackfriars Underpass and Upper Thames Street, have a 30mph limit that is scheduled to change to 20mph.

In addition to cutting top speed for internal combustion engines, the City of London is already piloting three “zero emissions zones”, or streets that only allow electric or hybrid vehicles.

Of course, the bigger issue as noted above, is that this is, above all, an exercise in environmental virtue signaling. Steve McNamara, general secretary of the Licensed Taxi Drivers’ Association, said: "Cutting the Square Mile speed limit won’t make much practical difference, as average traffic speeds in London are around 7 miles per hour. Reducing the excessive number of private hire vehicles is a better way to improve air quality.”

The efforts under way in the Square Mile dovetail with broader plans in Greater London to improve air pollution, which has been a priority of the city’s mayor, Sadiq Khan. As the FT notes, a new pollution charge for older vehicles driving in central London’s ultra-low emission zone (Ulez) went into effect last month, and is expected to cut pollution by encouraging drivers to upgrade to newer, cleaner cars.

Also on Friday, Heathrow airport announced it would implement the world’s first Ulez at an airport by 2022 and would begin charging all cars, taxis and private hire vehicles coming to car parks or drop-off areas, possibly from 2026. The Heathrow Ulez would impose minimum vehicle emissions standards, matching those of the central London Ulez, to persuade more people to take public transport or use greener private vehicles. Heathrow, the UK’s busiest airport, said the charge would probably be between £10 and £15, similar to that for the central London Ulez.

Over the past three years Greater London has also doubled the length of its protected cycling lanes, which now stretch across 116km. Within the City of London, the number of daily cyclists has nearly quadrupled since 1999.

Ironically, with Heathrow in the planning process for a third runway which would allow it to grow from 480,000 flights a year to 740,000, the airports has faced concerns that the sharp increase in passengers traveling to and from the airport will have negative environmental consequences.