Civil wars are the worst. They divide families and cause serious collateral damage. The National Trust and the Government began one when ministers published a new planning policy for England in July (1). With middle-class cousins – conservatives and conservationists – bearing arms against each other, bitterness and disillusion could have been expected. The death of sustainability, an ideal cherished by both sides, was highly unlikely, but there are grounds for thinking that it happened.

The core belief of NGOs since the Brundtland Commission in 1987, adopted by every business with a reputation to protect, died in crossfire over the Government’s introduction of a “presumption in favour of sustainable development”. Can this be true, I sense you asking? Isn’t the Government’s “presumption” actually singing the conservationists’ song? Surely sustainability isn’t being snuffed out, but getting a new lease of life? Not so, if we are to believe the trust’s chairman, Sir Simon Jenkins. Just the reverse.

“The old bias towards building in existing settlements is specifically revoked, effectively revoking a bias for sustainability. These weasel words make the document a lawyer’s banquet” (2).

Battle was joined in the media and Parliament as soon as the proposals were published. The Daily Telegraph (proving the civil nature of the fight) began a campaign against. Planning minister Greg Clark accused the Trust of “nihilistic selfishness” in exaggerating the impact on greenfield England.

The Chancellor and Communities Secretary said they were determined to “win the battle” on the planning reforms, which were vital for economic recovery. It was alleged that the framework had been co-authored by property developers with more than a passing interest, and the RSPB was somehow involved (search me). There was no denial.

The trust wrote to its three million members asking for support and claiming the Government wanted “to change the planning system into a tool to promote economic growth above all else”.

Admittedly, the aforementioned death went almost unnoticed amid the mayhem of hand-to-hand combat. But I can confirm that it did indeed take place, during a particularly bloody encounter between Sir Simon and Mr Clark, refereed by Jeremy Paxman with all the finesse of a cage-fight official (3).

Under close questioning, the Government’s cynicism in trying to give a green glow to what are no doubt perfectly honourable intentions became all too clear. Credibility, the lifeblood of sustainable development, was fast ebbing away. But in pressing home his advantage, it was Sir Simon who administered the coup de grace.

So weaselly was this ideal, he said, that it would take a half-decent barrister no more than an hour or two to prove that any development proposal in London was sustainable. No policy could survive such frank and devastating exposure. Sustainability as we have known it was no more. The implications will take time to sink in. Policy-makers, NGOs and businesses have for so long believed in sustainability as a third way, but not a lowest common denominator. We should have seen its meaning being stretched and its value reduced.

We should have treated it better. Yet this outcome of the English Civil War of 2011 cannot be the end of the story.

To mangle Voltaire’s saying about God, if sustainability no longer exists, it will be necessary to re-invent it. A more honest interface between economics and environment can replace the one we loved and lost.

Fortunately, there are responsible people on all sides able to make it happen. England’s need for more and different housing is acute. The Trust and Campaign for Protection of Rural England insist that enough brownfield sites already exist in the bulging land banks of developers.

However I agree with Peter Bill, former editor of Estates Gazette, who thinks they should argued for better housing – gardens, green space, families – rather than opposing a reasonable wish for simpler and faster planning (4).

The CBI and Engineering Employers Federation argue persuasively that investment in infrastructure (and therefore jobs) should be fast-tracked.

In the water sector we know about planning delay – and how to minimise environmental impact.

The Trust knows this too and will not oppose for the sake of opposing. The Government need not cave in to pressure, but must acknowledge the flaws in its proposals. It could lead a strong partnership for essential development with the trust and business as advisers inside the tent.

From now on green economics will focus on social value. Ministers in this and the last Government, in partnership with water and sewerage companies, have shown the way. The transfer of private sewers that began this month depends on confidence, inspired by a fine industry record, that problems can be solved and real value added.

Honest appraisal of society’s real needs, open debate, and reliance on tried and tested expertise can revive the ideal of development that deserves to be called ‘sustainable’.

Lessons can be learned from the experience of its predecessor.

Action inspires action. Stay ahead of the curve with sustainability and energy newsletters from edie