So long Chris Huhne, and thanks for all the fights

You can say what you like about Chris Huhne, and a lot of people have over the past four days, but he has certainly overseen an eventful 20 months for the Department of Energy and Climate Change (DECC) and the UK's burgeoning green economy.

As this weekend's countless (and possibly premature) political obituaries have made plain, Huhne was not to everyone's taste – there are plenty of people delighting in the resignation of a man who often created the impression that he said what he liked, and liked what he said. But despite a number of high-profile mis-steps he was, for the most part, a good friend of green businesses, and a powerful and vocal advocate for the low-carbon economy.

Huhne's personal and political faults have been well documented in recent days. He is an abrasive politician, driven not so much by overly aggressive instincts, but more by an unshakable self confidence in his own judgement that his opponents routinely deride as arrogance.

The stories of bruising exchanges with colleagues and opponents are legion. There was the infamous cabinet table row with Cameron and Osborne over dirty tactics in the AV referendum, the attack on the Conservative's 'Goebbels-like' campaign against the alternative vote, and ill-tempered scraps with Nick Clegg and Menzies Campbell for the Lib Dem leadership. There were whispers of officials who were disgruntled over Huhne's tendency to spend time engaged in political plotting, not to mention a fair few egos bruised by a willingness to challenge civil servants' advice. Then there were the attacks on both the "climate sceptics and armchair engineers" opposed to the government's green agenda, and the coalition of solar firms that challenged his department's ill-starred handling of cuts to incentives.

It is easy to understand why so few tears have been shed over such a high-profile setback to a promising political career.

And yet green businesses and green NGOs have plenty of reasons to regret the resignation of the energy and climate change secretary (to give him his full title). I understand the problems caused by newspaper space restrictions, but the media make a significant error when they describe the post as energy secretary. Being energy secretary would be a pretty easy job, being energy and climate change secretary is a historic challenge.

Huhne undoubtedly blotted his copy book with the chronic mishandling of cuts to solar feed-in tariffs, and angered old-school environmentalists with his support for nuclear power and offshore oil drilling. But his willingness to promote the green agenda, meet and engage with green business leaders, and stand up to high-profile critics of environmental policies, including his nemesis at Number 11, means Huhne leaves the UK's burgeoning low-carbon economy in better shape than it would otherwise have been.

Significantly, he won an early battle with the Treasury, deploying the prime minister's "greenest government ever" commitment to ensure DECC faced the smallest budget cut of any department bar International Development. He then managed the cuts that were imposed in a manner that minimised disruption and allowed quangos such as the Carbon Trust to build an independent future. Anyone doubting the importance of this achievement should witness the travails experienced by Defra over the past year, the bulk of which spring directly from the ridiculously deep budget cuts agreed by the department.

Huhne then stood up to Osborne and (shamefully) Vince Cable in successfully making the case for the UK to sign up to the fourth carbon budget, pledging to halve emissions against 1990 levels by 2025, and built on that success by leading the fight back against those vested interests and Conservative MPs calling for the UK to downgrade its green ambitions. While the prime minister remained silent, Nick Clegg proved strangely reluctant to play to his green base, and the chancellor launched a series of thinly veiled attacks on the green economy, Huhne was the government's most high-profile defender of green businesses and their potential to reshape the UK's economy for the better.

His series of three set-piece speeches over the summer on the need to get "off the oil hook" and build new industries of the future contained nothing that green business leaders and economists haven't been saying for years, but they offered an eloquent assessment of the huge benefits that will accrue from a cleaner approach to economic growth. They should be required reading for not just Huhne's replacement, Ed Davey, but for every member of a government that does not always create the impression it is fully signed up to green growth.

The remarkable manner in which Huhne managed to deliver these noteworthy achievements against a backdrop of a police investigation and tabloid sniping also gave DECC admirable stability. Since its formation in 2008, DECC has seen only Huhne and Ed Miliband serve as secretaries of state, providing the still young department with cabinet ministers who enjoyed the high-profile and political clout the job requires.

Huhne's political victories were accompanied by a series of policy successes that promise to reshape the UK's infrastructure over the coming decade. In fact, when Huhne looks back one of his biggest regrets will almost certainly be the fact that he got only about a third of the way through a programme that promises to lay the foundations for a complete restricting of the UK's infrastructure. The blueprints are all in place, but it will now be left to Huhne's successor to turn Electricity Market Reform, the Green Deal, the Green Investment Bank, the Renewable Heat Incentive and the feed-in tariff scheme into reality.

The onus is on Ed Davey and Nick Clegg (who surely now has to take on the more politically partisan role played by Huhne) to not only ensure these policies prove successful, but also repeatedly make the economic case for green growth. Any sign of weakness will be seized upon by the increasingly vocal critics of the environmental agenda, many of whom disguise their climate scepticism and anti-green politics behind spurious arguments about the cost of clean technology. If the Lib Dems need evidence of this threat they need look no further than last week's letter to David Cameron from about 100 Tory MPs attacking wind farm policy.

It remains to be seen if Davey has the influence, nous and appetite to drive the green agenda forward, although he made a good start this morning with the assertion that "there may have been a change at the helm, but there'll be no change in direction or ambition".

Green business leaders will be hoping he is true to his word and quickly builds on the successes Huhne enjoyed during an eventful 20 months at DECC. In an ideal world Davey will be able to deliver this progress without finding himself embroiled in quite as many of the political fights that Huhne apparently reveled in. But if a scrap is what is required, let's all hope he knows how to fight for green business interests.