The future of cycling giant Team Sky was thrown into doubt on Wednesday after British media company Sky announced it was ending a partnership that has delivered six Tour de France titles in the past seven years.

Team Sky have clocked up eight Grand Tour wins since their formation, but they have also been plunged into controversy for using special exemptions to administer drugs that can enhance performance.

The outfit, which has 322 wins in total since 2010, will operate for the last season as Team Sky in 2019 and could continue under a different name if a new backer is found, a Sky statement said.

“The vision for Team Sky began with the ambition to build a clean, winning team around a core of British riders and staff,” said team principal Dave Brailsford.

“We are proud of the part we have played in Britain’s transformation into a cycling nation over the last decade,” he added.

“While Sky will be moving on at the end of next year, the team is open-minded about the future and the potential of working with a new partner, should the right opportunity present itself.”

Sky’s announcement closes an extraordinary chapter in cycling that began with the dream of creating Britain’s first Tour de France champion – which seemed overly ambitious at the time.

But Bradley Wiggins made it reality in 2012, before Chris Froome won four Tour de France titles and Geraint Thomas became Sky’s third winner of cycling’s landmark event this year.

From marginal gains to mystery package

Deep-pocketed Sky are known for Brailsford’s meticulous and innovative application of ‘marginal gains’, the theory that many small advantages in areas as diverse as wind resistance, diet and sleep quality can add up to a significant improvement in performance.

However, Sky’s image was clouded in the controversy over so-called therapeutic use exemptions, after a damning British parliamentary report said the team crossed an “ethical line” by using the loophole to administer drugs to enhance performance.

The Commons digital, culture, media and sport committee report said MPs believed that triamcinolone, used to treat asthma, “was being used to prepare Wiggins, and possibly other riders supporting him, for the Tour de France”.

“The purpose of this was not to treat medical need, but to improve his power-to-weight ratio ahead of the race,” it added.

Sky were also in the crosshairs for a suspected anti-doping violation over a mystery package reportedly destined for Wiggins in 2011, although a UK Anti-Doping investigation concluded with no charges brought.

Sky was then caught in a long-running doping controversy that began when Froome returned an adverse doping test, for elevated levels of the asthma medication salbutamol, on his way to victory in the Vuelta a Espana in 2017. He was cleared 10 months later.

Team Sky also have plenty of detractors within cycling for tactics that many believe stifle racing.

Their superior budget has allowed them to employ riders who would be leaders elsewhere in a support capacity and effectively shut down attacks in the biggest races, something that has proved unpopular with many, particularly at the Tour de France.

Sky began its involvement with the sport in 2008, when it successfully teamed up with British Cycling to increase participation and support the country’s elite riders, who became a major force at world events including the Olympic Games.

“We came into cycling with the aim of using elite success to inspire greater participation at all levels,” said Jeremy Darroch, Sky’s group chief executive.

“After more than a decade of involvement, I couldn’t be prouder of what we’ve achieved with Team Sky and our long-standing partners at British Cycling.”

“I’d like to pay a special tribute to Dave Brailsford and the immensely talented team of riders and staff he has assembled at Team Sky,” he added. “What they have achieved together would have been beyond the dreams of many just a few years ago.”

US cable giant Comcast in October became the majority shareholder of Sky, coming out on top against Rupert Murdoch’s 21st Century Fox.

Fox, which owns a minority stake in Team Sky, has also confirmed it will no longer be involved in cycling after next year.