There has not been enough optimism in the great referendum debate.

If Scotland plumps for independence, there would be a huge opportunity for England as well as Scotland. England would have the chance to reinvent itself. But before the positivity, let's have a little (realistic) gloom.

The UK since 1945 has been beset by chronic decay, decline and deterioration. After the heroic but exhausting war effort Britain was almost bankrupt. It nonetheless embarked on a vast and bold social experiment: the creation of a welfare state, with a national health service as its centrepiece. This was possibly the most ambitious single initiative in British history, but despite the nobility of the concept, the outcomes have not been what its founders hoped for and indeed anticipated.

Meanwhile, for 75 years the UK has been struggling with chronic economic decline, as well as political decay. It may still be the sixth richest country in the world but most people who travel to other parts of Europe regularly know there are supposedly poorer countries where living standards are higher.

Every single UK post-war prime minister could and should be regarded as a failure. Nobody should blame them for this; they have had to struggle not just with regular financial crises, but with the continuing hangover of post imperial status.

Clement Attlee, the first post-war premier, was possibly the most successful; at least he ushered in the welfare state. Harold Wilson and Margaret Thatcher were potentially the most able; but Wilson was too obsessed with petty political intrigue, and his vision of a technology- driven economic miracle was a chimera. Margaret Thatcher had the strength and conviction to be an effective leader, but she was too keen to smash collectivism and replace it with an ill-thought out individualism.

Tony Blair was by far the most culpable of all the failed leaders, given the huge anticipation and excitement that greeted his election in 1997. He had a unique opportunity. But he frittered it away, although his Government did legislate for devolution to Scotland quickly and effectively.

He had an unfortunate taste for unnecessary wars, and his war in Iraq was at least in part responsible for the grisly and dangerous mess that now exists in northwest Iraq.

All post-war UK premiers have been presented with seemingly intractable problems. The worst has probably been social and educational inequality. Other unsolved difficulties have been the UK's fraught and sometimes catastrophic relations with the rest of Europe; festering internal tensions caused by issues of ethnicity, race and immigration; continuously poor industrial productivity; and rapid changes in sexual and social values.

This last might be seen as progressive; in the 1940s and 1950s the UK was far more grim, repressed and buttoned up than it is now. Yet despite the austerity and even privation of the immediate post-war years, I suspect most citizens were happier then than they are now. An understandable social and cultural liberation has removed many restraints, but now there is a pervading sense of unease about the British way of life, and this is not helped by an enormously influential entertainment industry which appears to be constantly mired in sleaze.

All this could dramatically change after September 18, for England (and to a lesser extent Wales and Northern Ireland) as well as Scotland.

Scottish voters have the chance to give England, as well as Scotland, a completely fresh start. The referendum is not only about Scotland's future; it is about the future of England, and the rest of the UK.

If Scotland becomes independent, we shall have an obvious and realistic opportunity to start anew, and embark on the building of a new and far better society. The same applies to England in almost equal measure, and this is too easily forgotten.

Alex Salmond can speak about Scotland, and indeed is expected to do so: that is his job. But which UK premiers have been comfortable speaking about England? I genuinely believe that if Scotland votes Yes, we will have a truly exciting win-win: Scotland wins, and England wins too.