The environmental movement has made great strides in the last 10 years. It was a movement on the margins looking in; now the environment is centre stage. The question is, how do we capitalise on that and more deeply engage the public, business and government in caring for our environment?

Recent debates about UK planning laws have shown that the environmental movement can have incredible traction when we do engage the public. That’s what I’ve been trying to do at the National Trust for the last 12 years, and in this article I draw on some of the lessons I have learnt in my time there.

From the first, I was struck by the National Trust’s unique proposition to the nation. We look after over 250,000 hectares of countryside, 700 miles of coast and more than 300 historic houses and gardens, forever, for everyone. Last year, we had more than 19 million visitors to our properties, tens of millions more to our open spaces, and achieved a total of four million members. In the process, we have become a large charity with a turnover of £450 million.

Our promise to the nation is that we will do this forever: this is as clear a sustainability brief as I can find. We have to sustain what we do in perpetuity. And that is what drives the National Trust forward – our triple bottom line of people, finance and conservation.

Like any organisation, we have innumerable short-term needs and challenges. But what marks the Trust out is that our long-term obligations speak as loudly to us. We plan for our properties on a 75-year time horizon (a working definition of ‘forever’). And in any year we have to find the money to repair roofs and restore upland peat ecosystems – both very expensive and with no financial benefit – as well as to invest in catering and retail, both of which need to bring an immediate return. We want to reach many more people and to grow our membership base – but not at the expense of the fabric of our places. We are not perfect at balancing these competing needs, but using a triple bottom line approach helps us make better decisions. Above all, we need to inspire and engage people – we can do nothing without them. That’s what has been at the heart of our changes over the last decade.

Let me talk about two recent Trust campaigns that have given me hope for the future.

Planning Campaign

At one level, last year’s planning campaign, which the Trust led, looked like a traditional battle: growth versus no-growth. On the contrary, though, for the National Trust it was really about how we grow rather than whether we grow.

In the aftermath of the Second World War there was a sense of determination and purpose about the type of country we wanted to live in. In those years legislation was passed to establish the welfare state, the National Health Service, universal access to education, the national parks, access to the countryside, and the land-use planning system. The planning system achieved some vitally important safeguards: separating town from country, using land efficiently, and stopping urban sprawl.

In 2011 the draft National Planning Policy Framework put all of that up for grabs. It threw out the long-standing principle of balancing social, environmental and economic goals in order to put the economy first.

In an unusual step for the National Trust, we decided on a full-throated public campaign against these changes. The early Trust had been in at the start of the planning system in the 1920s and 1930s and we were not going to stand by and watch it being dismantled. Special places everywhere would be under threat.

Against the odds, we succeeded. The final planning proposal put forward by the UK government is a much better, more balanced document. Much remains to be done to implement it effectively – but the framework no longer prejudices long-term sustainability.

I am convinced that the government listened because the Trust was felt to speak for the nation – and in particular the quarter of a million people who signed our petition. Public engagement was central to that success.

Children and Nature Campaign

The National Trust ran another utterly different campaign in 2012: 50 Things to do before you’re 11¾. This was a fun campaign, harking back to what many feel is the lost innocence of childhood. All that summer we saw parents teaching children to fly kites, skim stones, get muddy and climb trees.

The campaign garnered enthusiastic support from child psychologists, education experts, parents and the media. It demonstrated a hunger for Nature and authentic experiences, and it highlighted the real risks we’re exposing children to by denying them access to Nature. The background was well-researched – we had uncovered evidence that, for example, three times as many children are taken to hospital every year for falling out of bed as falling out of a tree – but at its heart the campaign spoke to a human need for contact with Nature.

In September we brought together professionals from a wide range of groups interested in getting children outdoors and closer to Nature. We agreed on the problems; the conference was about finding solutions. We agreed too that a mix of government action, policy and practical alignment and personal choices would be essential. And we put in place a cross-sector partnership to coordinate our efforts – and ensure we would not preach, but inspire.

The lesson both these campaigns have taught me is the need for the environmental movement to engage with people rather than focusing just on ‘policy wonk’ political lobbying. Otherwise we risk being sidelined in the current political debates, being characterised as anti-growth and marginal.

In fact, the values we stand for have never been more centre stage. We have seen an upsurge in interest in beauty and heritage in recent years, a rejection of wholly material values in favour of more physical and spiritual refreshment. The current economic climate is tough – but people are voting with their feet for things that don’t cost much but are beyond price in their value.

We all share a vision of a more sustainable future, but we can’t achieve that without the engagement of people. For many right now, economic difficulty is the visible reality. But if we can articulate a better future, where there’s more to life than money and where people are healthier, happier and more satisfied with their lives, that will start to shape the choices we all make.

It’s not just about where development and infrastructure go, and the kind of development (including social and green investment) we want, but a recognition that the things we care about – the environment, Nature, beauty, quality of life – are not luxuries but essentials.

One of the National Trust’s founders, Octavia Hill, a housing reformer, said: “The need of quiet, the need of air, the sight of sky and of things growing seem human needs, common to all.” I firmly believe, 100 years on, that this holds more true than ever.

This is an edited version of the talk Fiona Reynolds gave at the Resurgence Trust Festival of Wellbeing in London last year.

Fiona stepped down as Director-General of the National Trust in November 2012. She is currently writing a book about her 12 years there.