AN engine maker powering distinctive London buses says it remains unfazed despite plans to end further expansion of the fleet.

Cummins has vowed to retain its position at the pinnacle of the UK bus market when Transport for London (TfL) stops buying doubledecker Routemasters.

London mayor Sadiq Khan previously warned the hybrid- powered buses were too expensive to run, and TfL has confirmed it will “discontinue purchases of new Routemaster buses”.

Darlington-based Cummins has supplied engines from its North-East plant for around 800 Routemasters, which officials say cut CO2 emissions by about 30 per cent.

However, the vehicles, built by Northern Ireland’s Wrightbus and dubbed Boris buses after their 2012 introduction by former mayor, Boris Johnson, are now deemed surplus to requirements, with TfL saying it wants to halve spending on its citywide bus fleet from £82m to around £40m a year by 2021.

But Cummins, which has been in Darlington for more than 50 years, says while the news is “disappointing”, its reputation provides bosses with confidence for the future.

A spokesman also added the business will be well placed to support TfL in the future, whichever direction Mr Khan opts to take on transport in the capital.

He said: “Should Sadiq Khan choose to stop ordering this model of bus moving forward it is obviously disappointing.

“However, as we are the leading engine supplier to the UK bus market, we would hope to be in a good position to support his future plans, whatever they may be.”

London’s new Routemasters, designed by Thomas Heatherwick, were a nod to the days when the original models, which became as synonymous with London as Big Ben and Tower Bridge, were introduced in the 1950s.

The last of the popular, open-platform models was withdrawn from regular service in December 2005, although some still run on tourist routes.

When bringing them back, Mr Johnson said they represented a “masterpiece of British engineering and design”.

However, Mr Khan was more cautious during last year’s city mayoral campaign, suggesting he would look at stepping back from any further purchases to help with savings and create funds to pay for a hold in fares.

Cummins has vast experience of supplying engines for transport operators.

The company previously revealed it had supplied cleaner engines to manufacturer VDL for vehicles in Germany, Belgium and Finland.

According to bosses at the time, the greener Euro 6 engines, built to deliver better fuel economy, were identified for use in more than 200 buses by Germany’s largest operator, Berlin Transport Authority.

The business’ engines were also chosen to power a number of De Lijn hybrid buses in Belgium.