If there was one thing you could rely on in this fast-changing world, it was that the Conservative party would be conservative. Everything else might be upside down, but at least you could trust the Tories to defend those institutions that were timelessly and for ever British. If nothing else, the Conservatives would conserve.

Of course, there are plenty who would say that ceased to be true years ago. For old-school Tories, the rot set in about the time the party came out against hanging and the birch, the cause finally lost with the advent of David Cameron and his Notting Hill modernisers. Nevertheless, and despite the radicalism of the Thatcher revolution, most Britons still regarded the Conservative party as the natural defenders of our customs and heritage. Whether it was protection of the countryside or the nostalgic hope that Britain, even without its empire, would punch above its weight in the world; whether it was passing on the wisdom of elders to future generations or the hallowed principles of charity and thrift, the Tories held their place as the designated defenders of tradition.

Until now. After less than a year in government the Conservatives have revealed themselves as a threat to the very values they once sought to protect. Despite his weekend attempt to safeguard Britishness against the supposed menace of multiculturalism, it is David Cameron who is taking the axe to much that Conservatives once regarded as central to the British way of life.

And axe is just the word for the policy that, more than any other, embodies this strange abandonment of Tory principle: the proposed sell-off of the nation's woodland. Forget the reversal this represents for a Conservative party that five years ago showed off its greenness by replacing its old torch logo with a tree. This marks a break from a Tory cast of mind that has endured for centuries: Tories in the age of Wellington would have regarded the forests as the heart of England, part of the nation's sacred patrimony too precious to be sold off for fiscal pocket change.

Had another political party suggested such a plan, it would have faced a howl of Tory pain and fury that anyone could treat so callously what is not just a living landscape but part of the nation's folk memory. This was the historic Tory role, to fend off those modernising brutes whose worship of tomorrow left them blind to the value of yesterday. Yet now the Conservatives must look in the mirror and realise: "The enemy is us."

But surely, you say, patriotism remains safe in Tory hands, especially in a week when the PM wins plaudits from Norman Tebbit for his speech on race and integration. Alas, you can make no such assumption. For if traditional Tory patriotism called for Britain to walk tall in the world, exporting the language and civilising values of Shakespeare and Milton to the furthest, darkest corners of the globe, then that faith too has been betrayed by today's Conservatives.

By insisting on cutting the budget of the BBC World Service, the government has cast aside what would once have been Tory guiding principles. The BBC estimates that the cuts will not just shrink the payroll by 650 journalists, but shrink the audience by a staggering 30 million listeners. Britain will no longer be the home of the world's biggest broadcaster, losing that pre-eminent place to the Voice of America.

The 19th-century Tories who once gazed at the globe from their high-backed leather chairs in Pall Mall's clubs would be appalled: they knew the value of soft power. They would have realised the enduring benefit for Britain in the villagers of Africa, China or India for ever associating the free circulation of ideas with a British accent. With five language services closing entirely and the daily arts programme slashed by a third, Bush House insiders discern a direction of travel that ends with the World Service reduced to a glorified rolling news operation, lacking the country-by-country specialisation and arts, music and drama that made it nothing less than a global force for enlightenment. And all for the sake of a measly £19m in savings this year, money that could have been found in the Department for International Development's petty-cash box. Introspective philistines would always have made such a move. But this is not what you'd expect from a Tory party that once sought for Britain a unique role in the world.

And who would have predicted that the librarians' executioner would be the Tories? In the age of the Nook and the Kindle, the library may indeed look old-fashioned – but Conservatives used to teach the rest of us that old didn't mean worse. Libraries were repositories of the wisdom of the ages, places where the young – especially those whose homes included no books and no quiet in which to read them – could find refuge. Where they could, in the best Tory spirit of self-reliance, educate themselves. Yet now a Conservative-led government slashes council grants, knowingly passing the death sentence on these oases of learning.

There are surely few more Tory virtues than charity. Yet it is charities and voluntary groups who are feeling the sharp edge of the Cameron blade more than most. Just this week, the Conservative council of Hammersmith and Fulham moved to sell off nine buildings that house charities, so triggering the likely closure of up to 30 community groups. What of the timeless Tory value of thrift? It looks imperilled when those most skilled at combating debt – the highly trained staff of the Citizens Advice Bureaux – face a 45% cut in funding.

All this amounts not just to an assault on the Toryism of the ancient past; it also entirely undermines Cameron's own signature idea of the "big society". So why is it happening?

One theory is that it represents victory in a long-running struggle for the soul of the Conservative party, with the neoliberal Thatcherism of George Osborne winning out over Cameron's one nation Toryism. But that's a trifle unfair to Thatcher. Yes, she was unsentimental in her willingness to tear up the past. But her target was usually those institutions she deemed ossified and stuffily establishment. There is no such logic underpinning this government's assault: it is an indiscriminate trashing of our collective heritage.

And it will have political consequences. Tory MPs, faced with constituents outraged by the loss of a library or wood, will rebel. More important, if the Conservatives are vacating this Tory space, someone else will fill it. That could be pressure groups. Interesting that the Countryside Alliance has organised no mass march on London to protest at the great forest sell-off: perhaps they should rebrand as the Hunting Alliance – since that's clearly all they really cared about.

Which leaves an unexpected opening for Labour. In the Blairite heyday, New Labour often found itself on the opposite side of traditionalists – supporting 24-hour drinking, casinos or high-street-destroying supermarkets in order to be "pro-business". Breaking free of that neoliberal orthodoxy could enable Labour to stand up for longstanding institutions that people value, whether that's a local post office or copse of trees. Encouragingly, Ed Miliband has already taken some steps in that direction.

For today's Tories, the challenge could be harder. They have to wrest back a party whose deficit monomania has made it out of touch with the country – and out of tune with what should be its deepest values.