For almost 400 years, Hackney Carriages have been a familiar sight in London. With red buses, Nelson's Column, and Buckingham Palace they are iconic symbols of the capital and feature on countless tourist souvenirs.
Of course, they are more than just an icon, they help to keep one of the busiest and most vibrant cities in the world moving.
The black taxi, and the cabbies who drive them, are a little like marmite, you either love them or hate them - probably depending whether you are desperate to catch a train or get home after a night out, or whether you are a cyclist or motorist who has had a less than convivial 'encounter' with a cabbie.
But, love or loathe them, there is no denying the fact that, without black cabs, London would be even more congested and traffic bound than it already is.
The iconic black cab is getting a makeover. The BBC recently reported on (not so) secret tests being held in, of all places, the Arctic Circle on a new black cab.
The good news for fans of the traditional cab, and doubtless for manufacturers of souvenirs, is the shape and colour of the taxi will remain the same. What will change, however, is the sound and, crucially, the environmental impact of the cab.
At least that's the plan.
Diesel cars are getting a bad press at the moment and vehicles which were once thought of as eco-friendly are now known to be causing horrendous air pollution . A problem which Londoners are all too familiar with.
With black cabs producing around 15% of the nitrogen oxides belched out by vehicles in central London, clearly something needs to be done.
The vehicles being tested in the Arctic have electric engines and, according to the manufacturers, emit almost zero emissions and are virtually silent when driven.
Though they will be built in Coventry, the new cabs were being tested in the Arctic to see how they performed in the clean but brutal conditions. And, presumably, to showcase the vehicle to other cities around the world which also have pollution issues.
However, with London mayor Sadiq Khan already promising that, by 2018, all new taxis must be capable of zero emissions, the new vehicles will soon be appearing on the roads of London. Or will they?
Whilst everyone would agree zero emission black cabs are desirable, even essential, what exactly is the likelihood of them appearing in large enough numbers to make a positive difference in the fight against pollution?
The answer, as things stand, is probably very little.
It's a refrain often heard from exasperated punters who have watched the meter speed round faster than Lewis Hamilton's Mercedes, but this time it is the cabbies who are price watching.
The new electric powered cabs could cost £40-£50,000. A hefty chuck of change which would require more than a few trips south of the river for most cabbies.
It's a price which many cabbies, already burdened with the time and cost of acquiring the knowledge , not to mention plate, insurance, and garage fees, may not be willing to pay.
Added to the cost of the vehicle itself is the infrastructure which would be needed to keep them running. Hundreds of charging points would have to be positioned across the city, an expense which, presumably, would have to be met by the capital's taxpayers.
The original taxis in London were horse drawn Hackney Carriages. Undoubtedly environmentally friendly, any emissions could be used to help the crops grow. Might we be going (almost) full-circle and seeing green vehicles ferrying passengers around the city?
The cost implications aside, though someone is going to have to come up with a subsidy programme to help cabbies afford the new vehicles, zero emission cars are surely the way forward. Certainly, anything which can help in the fight against air pollution will certainly be welcomed by all Londoners.