Mary Dejevsky: It will take more than these seeds of doubt over drugs to stir up the Shires

There is more human charity and massively more social liberalism than the Shires are ever credited with

His adversaries believe that we need to know a great deal more, and so - with politics or prurience aforethought - do sections of the media. Not by chance, it seems, they have homed in on just one question: did he or did he not take drugs? They know that, just by planting the doubt, they will draw out fear and loathing in the Shires.

Ah, the Shires ... that true-blue heartland, that England of olde, where ladies of a certain age potter about in their Morris Minors; retired colonels play cricket on the green and there really is honey still for tea. The calculation of those gunning for Cameron is that the fortunate residents of this paradise will abandon David Cameron in their droves if they think he has ever come within sniffing distance of a banned substance.

And maybe they will. But I am betting they won't. For something has been stirring in the shires over the past decade or so, and those constituency Tories are not nearly as insulated from the rest of the country as is commonly supposed by those who rarely venture out of their cities. Visit a town market, take a rural bus, sit in the village tea shop and listen to the conversation.

You will hear bigotry there, as you will hear anywhere. There will be furious opposition to plans for "affordable housing" on the edge of a chocolate-box village. There will be resentment against social security "scroungers" from the same people who pay their builders in cash. And there will be a measure of gut anti-European sentiment , as in "nothing good ever came out of Brussels".

But there will also be more human charity and massively more liberalism in social attitudes than the Shires are credited with. Let me hazard what you will not hear at the market or taking tea with the Tory ladies. While you might hear the odd reference to "feckless" single mothers, you will not hear any condemnation of "illegitimate" children, and precious little talk of "living in sin". You might hear the state of marriage being discussed approvingly, but you will not hear people inveighing against cohabitation. You will not hear of people expelled from their social circle because they are divorced. And you won't, as you might in the United States, hear a diatribe against gay marriage.

Gay people are widely accepted, living singly or as couples. Rather quietly, someone's granny might say to someone else's granny over coffee: "You know, I think so and so might be gay." But it is stated as a curiosity of life, a rather daring thing to say, rather than as social censure. Aids is discussed as an illness that needs the latest treatment, not as a sin. And do you remember the outcry about women priests and how they would not be accepted in many parishes? Well, some of the best-loved and most attentive parish priests are women. They have become part of the community.

Not everything has changed everywhere, but much has, and it is a change that spans the generations. Just because there are more older people living in the Shires than in the inner cities and the pillars of the constituency parties tend to be Tories of a certain age does not mean that social attitudes there are stuck in the 1950s. It is among the "granny" generation, indeed, that the shift has probably been most remarkable.

Remember: the grey-haired ladies who pour the coffee after church or cut the sandwiches for constituency teas grew up at a time when unmarried daughters were banished if they became pregnant and illegitimate children were shunned as bastards. They grew up to marry and have children, not to have a career. Divorce disqualified the woman from polite society. As for gays - they were mostly in the closet, out of sight and out of mind. They expected parish priests to be men with a homely wife and family. And if they needed medical treatment, they expected the doctors to be patrician men and the nurses to be nice young women.

Their world has changed around them: the war, the Sixties, the Pill, Thatcherism ... everything. But, as a generation, they have changed, too, and adapted - admirably so. And one reason is surely that it is their sons and daughters and grandchildren who have been responsible for smashing so many of the taboos.

Where, as young parents in their 20s and 30s, they might have condemned whole groups for their lifestyle or behaviour, they now have at least second-hand experience of dysfunction. Now, even the most conventional of families has probably broken the bounds in one way or another. Many years ago, families had the occasional "black sheep"; now there are multiple gradations of grey. Look at the middle generation of the Royal Family, for heaven's sake.

The question David Cameron faces is whether the Tories of the Shires consider a passing acquaintance with drugs, of whatever category, as somehow different from family dysfunction. Does a "youthful indiscretion", as the present US President put it, disqualify someone from high political office? George Bush never answered the question straight, and still managed to get himself elected. And all the signs are that Mr Cameron will benefit from the same forgiving instinct as Mr Bush did. If it is unambiguously in the past, it is a matter of private life, and everyone - even a politician - is entitled to some privacy.

The public reception Mr Cameron has received so far has reinforced this. On the BBC television programme Question Time on Thursday, he was asked the drugs question for the umpteenth time and admitted, also for the umpteenth time, to "a normal university experience". Pressed for a "yes" or "no" answer, he said that individuals were "allowed to have had a private life before politics in which we make mistakes and we do things that we should not". He was applauded. When he added that he thought it would be "a very sad day" if people wanted "machines as politicians who had never done anything wrong", he was cheered. And this was not an audience of hard-bitten young Londoners, but a mixed-generation audience from Co Durham.

David Cameron has been flavour of this week, but this is no guarantee that he will be elected the next leader of the Conservative Party. If he fails, however, he should fail because his political experience or his policies are judged to be inadequate, not because of anything he did (or did not do) at university. It is gratifying to find not only that the country at large seems to believe this, but that the preponderance of the Tory heartland seems to believe it, too.

m.dejevsky@independent.co.uk