Viewed from a distance of 50 years, 1953 seems a suitable year for affectionate nostalgia, at least for the British. A lovely young Queen was crowned, Everest was conquered, the spirit of the Festival of Britain, held just two years earlier, was still breathing optimism over the nation despite bombsites and continued rationing. The Korean War ended and, to garnish the goose, Prime Minister Churchill was awarded the Nobel Prize for Literature.

It was also an important year in science, although the impact of a discovery then made was apparent only to a few: the correct description of DNA. Because this discovery is now beginning to transform medicine and soon, perhaps, human nature itself, 1953 is a key year indeed.

These happy events were a relief after the grim wartime struggle and the years of austerity that followed. It seemed that bright morning had come at last. And because of the social changes first reflected in the landslide Labour victory of 1945, more of the British felt that the morning was dawning for them.

But does 1953 deserve the rosy light being shed on it? The optimism then felt was real enough; but what people did not realise was that the gargantuan effort of war had fatally undermined not only pre-war society, but the economy, the empire, and Britain's place in the world. The dawn was, in short, a false one.

The disaster of Suez just three years later proved the point. For the prescient, auguries were obvious in important changes occurring elsewhere in the world in that year. Eisenhower became President in the United States prompting Adlai Stevenson to say: "the car dealers have taken over from the New Dealers". Stalin died, and the USSR revealed that it had a hydrogen bomb. Unbeknown to the British public, its wartime government had been obliged by America to promise to dismantle the empire in return for aid.

The problem with the economy was not just a result of the war's staggering cost, nor of the damage done by enemy bombing and the distortions caused by wholesale redirection towards wartime production. A major factor was the new power of the trades unions, which for three decades after the war kept a stranglehold on efforts to modernise the economy. They had become interest groups careless of wider responsibilities, concerned only to extract the best terms for their own members at no matter what cost to other unions members and the economy at large.

If the most visible sign of the British lion's loss of teeth was Suez, the most far-reaching was the difficulty of keeping the empire, anyway due for demolition, on an even keel while demolition happened. British troops from Kenya to Malaya were engaged in combating insurgencies, and one of the Dominions - South Africa - adopted apartheid, which in 1961 led to its relinquishing Dominion status and leaving the Commonwealth, developments Britain was powerless to influence.

The most malignant cloud on the horizon, however, was the Cold War and the threat posed by nuclear weapons. The McCarthy era in the US had just ended, but the hysteria which prompted it was still alive. In a few years, the world would come to the brink of disaster in the Cuban missile crisis. In 1953, Bertrand Russell was already warning of the dangers of living in an atomic age; from then until the detente of the 1970s, the danger that civilisation might be destroyed in a nuclear holocaust was felt by many to be imminent, and by almost all to be the background to the otherwise bright, even garish, optimisms of the age.

And even these seem odd in retrospect. The second-class status of women, the oppressive hand of conventional morality on sex, marriage, censorship and abortion, and the paternalist grip of backward-looking Establishment attitudes - from the BBC to the churches - were still in force. Such was the moral stiffness of the time that divorce still attracted scandal and stigma. And as for homosexuality: remember that the genius Alan Turing committed suicide because of arrest for "indecency" in a public lavatory.

In these latter respects there were soon dramatic changes for the better. But many of the negatives clustering on 1953's horizon are still with us: the parlous state of most of what used to be Europe's empires in Africa and Asia, too many dangerous weapons in unscrupulous hands, and the legacy of an unequal international resolution after the Second World War. Just how wrong we were to be optimistic in 1953 still remains to be seen.

AC Grayling's new book, 'What Is Good? The Search for the Best Way to Live', has just been published by Weidenfeld and Nicolson.