It will now cost £21.50 to drive a pre-Euro 4 vehicle into the capital, affecting any fleets that run older diesel and petrol models, typically registered before 2006. The charge is expected to affect 10,000 pre-2006 vehicles and tighter restrictions are likely to be introduced over coming years.

Other UK cities likely to follow London’s lead include Birmingham, Leeds, Nottingham, Derby and Southampton.

As a result, the fleet and SME division of the AA motoring services group is calling for the automotive industry to increase its support for SME customers.

Stuart Thomas, the AA’s head of fleet services and SME, said: “As emissions reduction becomes a focus for the UK’s large cities, businesses are under pressure to futureproof their fleets to ensure they comply with any future targets.

“Fleet managers feel required to investigate alternative fuel sources, but they may not have enough information to make strategic decisions, or feel supported by the industry to take an informed step forward.

“Small businesses are likely to be hit hard by the introduction of the T-charge, which almost doubles the cost of driving a vehicle through London during peak hours. Fleets are the backbone of British business, and need more guidance to help them to make the most of the upcoming EV revolution. We urge the automotive industry to provide the support businesses require to help them to anticipate upcoming legislation and reduce costs.”

In five years’ time, 63% of SMEs and businesses expect to be using alternative fuels to power their business vehicles, according to the second annual Operational Fleet Insight report, produced collaboratively by the AA and BT’s Fleet Solutions.

The report found that SMEs are increasingly worried that manufacturers aren’t always treating them as a priority when it comes to advice and support due to their small fleet size.

Businesses can check if their vehicles will be affected on the T-charge checker developed by Transport for London (TfL).