The French have an admirable phrase - "why make it complicated when you can make it simple?"

That sentiment would not have found much favour with my predecessors. Last year when I began to rethink national planning policy, I asked for copies of the existing policy. It had to be carried into my office in boxes.

I could see immediately that this gave rise to two problems:

Firstly, only a planning specialist could possibly be familiar with it all. This makes a nonsense of a planning system that was intended to make local communities, not planning lawyers, the people who make the important decisions.

Secondly, the more words that were added, the less clear it became in terms of what national planning policy was actually trying to do.

The new draft National Planning Policy Framework that I published for consultation last week addresses both problems. For a start it reduces over 1,000 pages of documentation to just 52 - anyone interested in planning can now be fully familiar with national policy.

Just as importantly, the purpose of the planning framework is now plain for all to see. It is to help achieve sustainable development. We need to be clear-sighted about the need for growth. We need more houses: for young people; for families; and for older people living - thankfully - longer than they ever have before. It may be convenient to imagine that our population is stable or shrinking, but this is just plain wrong - the fact is that our population is growing. And yet, under the last Government, the number of new homes built fell to a lower level than in any year in our peacetime history since 1924 - when our population was only three-quarters of what it is now. To fail to provide the houses we need is to condemn today's young people and their children to overcrowding, homelessness and poverty driven by soaring rents and house prices. No progressive should have any truck with a course of such cynical selfishness.

The same is true of growth in the commercial economy. Growth - that is to say, jobs and wages for people - doesn't happen in the abstract. It happens in particular places. And almost every one of those places requires new buildings and new infrastructure to support it. To be against new buildings and new infrastructure is to be against growth, which is in turn to be in favour of people becoming poorer than they are today - something that should be unconscionable to anyone with a concern for the wellbeing of their fellow man.

There is no reason why growth should mean ugliness. It can - and should - improve our physical environment. Anyone who thinks otherwise should take a tour around our great cities, towns and villages and consider the diminished place that Britain would be if our forebears had been adamant in their opposition to new development.

And other attitudes of the last decade - which are alien to what we have historically thought - also need to be re-considered. In particular, the idea that every blade of grass outside our towns and cities is sacrosanct - and that urban green space should be sacrificed to preserve it - betrays a degree of inhumanity to people who may not live in the countryside, but who still have the same appetite for nature and greenery and life.

For all of these reasons, the new draft Framework has, at its heart, a statement of powerful simplicity: if a proposed development, or plan, does not give rise to any problems, then it should be approved without delay - a presumption in favour of sustainable development.

But this does not show a green light to development everywhere. Local plans will continue to set out what would be unacceptable, and neither plans nor developments may compromise national requirements for sustainability. The new draft Policy Framework proposes no change in the approach to sustainability that has been used by previous Governments. Indeed, it reiterates the Brundtland Commission's classic definition of sustainable development - which is development that "meets the needs of the present without compromising the ability of future generations to meet their own needs." And the Government proposes no change to more recent formulations, such as the 2005 UK sustainable development strategy.

To give some specific examples, the protection that the Green Belt has enjoyed in the planning system continues. Indeed, to recognise the importance of green space within towns and cities as well as outside them, a brand new designation is available to local people (through their neighbourhood and local plans) to protect valued green space wherever it exists. There is no change, either, in the position of Areas of Outstanding Natural Beauty, Sites of Special Scientific Interest, National Parks or other protected habitats. Neither is there any change in the status of countryside outside these specially protected areas. Local councils will still decide through their plans what land to allocate - with the crucial difference that these local plans will no longer be overridden by the diktat of unaccountable regional quangos, which are being abolished. The protection of our historic environment - from archaeological sites to civic conservation areas - also continues. And good design - which is vital if the choices made by this generation are to benefit the lives of future generations - is given a higher status than ever before.

Given all this, the initial reaction of one or two organisations who share my lifelong commitment to our environment was way off-beam. One group even forfeited seriousness in favour of parody: juxtaposing an aerial photograph of Los Angeles - the 100 mile wide city - with a misty meadow and claiming this was what lay in store for our capital. In fact, there is - as everyone knows - a very good reason why London doesn't look like Los Angeles: the Green Belt, which maintains its strong protection.

Most people who have worked with me during the last year would, I think, recognise that I am someone who listens carefully to constructive comments. The Localism Bill has benefited considerably from the active engagement of people who have made practical suggestions. In distilling over 1,000 pages of national planning policy into 52 it would be surprising if everything was expressed perfectly - though it is a huge advance on what it replaces - and some policy choices that have been made bear reflecting on. For example, we have toughened up the 'town centre first' policy by requiring the impact on town centres of proposed new developments to be considered over the next decade rather than just five years, as is currently the case. On the other hand, we're proposing to exclude small-scale business centres in rural areas from the town centre first policy. Have we struck the right balance? I am keen to hear views. That's why I have insisted on a very wide consultation on the draft Framework and I look forward to receiving responses. Suggestions are actively encouraged. But if they are to be worthwhile, they should be serious - detailed, specific and practical.

Resolving the two problems of planning policy I identified - its inaccessibility and its lack of focus on achieving sustainable development - is the purpose of our reform.

The new National Planning Policy Framework is a big chance to make Britain better for future generations as well as our own. That is what sustainability is all about. We are determined that the beguiling convenience of the present must not overshadow the needs of the new generation and those that will follow them.

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