After four days at Sandy Hook I have returned home to Washington. I drove my children to school this morning and turned the radio off. The news was still wall-to-wall Newtown, and I wanted to have a conversation about Christmas and cookies and all the innocent stuff that has been spoiled by the carnage.

In Newtown, Connecticut there are 26 Christmas trees adorned with teddy bears and baubles and pictures. They stand close to the school. They are memorials with the grim presence of tombstones.

The Christmas symbols of joy have been turned upside down in this once pristine New England hamlet. My daughters smile and laugh as they trot off happily to their last day at school before the holidays, dimly aware that somewhere else in America something terrible, unspeakable has happened to children just like them.

Now I am alone in the car and the radio comes back on. I am informed that even the National Rifle Association (NRA), an organisation that can make or break a politician’s career,  Democrat and Republican,  is considering a contingency from its corporate bunker outside Washington.18 newtowntree r w Christmas turned upside down by the carnage in Newtown

On cable TV, the former Republican congressman Joe Scarborough’s meltdown mea culpa about assault weapons is played ad nauseam. Senator Joe Manchin of West Virginia, a gun-loving Democrat, says he has just come home from a deer hunting trip with his kids but he is in now in favour of banning some assault weapons from public use. “Who needs a machine gun to hunt deer or pheasant?” he says. It has become a commonly pronounced concession, as if that was ever in question. Who indeed?

I still think, though, that this massacre has produced a watershed. The president is emotionally invested. The gun lobby has been so shamed for now that not one senator supported by the NRA was prepared to go on TV or radio at the weekend to defend the second amendment of the constitution – the much-quoted right to bear arms.

But the statistics are sobering. There is almost one gun per person in this nation of more than 300 million. One third of households own them. The five guns kept by the killer’s dead mother Nancy are only two above the average for each gun-owning household.

In Michigan they have just voted to allow teachers to carry concealed weapons in class. Who knows, this may indeed have prevented Friday’s massacre. But guns in school will more likely lead to a thousand OK Corrals.

The best President Obama can hope for is a return to the ban on assault weapons that Bill Clinton introduced in 1994. It was full of loopholes and it expired after a decade. But at least it was something.

Read more: School shootings – horror, shock and calls for gun controls

There are many reasons for America’s love affair with guns: the frontier culture, the vast distances which mean that in some states like Montana it really does take an hour for the cops to arrive at a scene, the romance of hunting, the cult of the individual who is taught to fend for himself and forever tries to get government off his back.

Fair enough. But when you combine an 18th century rationale for guns with a 21st century obsession with violence in video games, films and online, you’re in trouble.

My school drive has finished and I park the car outside our house, which is next to Sidwell Friends School, the school where the Obama children go. I count the usual security: two black armoured SUVs with six secret service agents in situ, another six secret service patrol cars with two agents each dotted around the two streets. I know there are two agents in each class room and two in the corridor outside.

The caretaker of the school told me that his holiday has been ruined by another Swat team drill. Happy Christmas!

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