Debo was always my mother's second favourite Mitford sister. She felt that Deborah was a good sort - a kind of People's Aristocrat, probably saved for the nation and part owned by the National Trust. And she would have approved of the Dowager Duchess of Devonshire's column in the latest issue of the otherwise despised Spectator magazine, lamenting the closure of her local post office. Mum also liked Ken Livingstone and Ken, too, wants to keep post offices open.

Who doesn't, except - perversely - whichever government is in power at the time, and the Post Office itself? To try to search for argument about the pros and cons of branch closures is to discover the most one-sided debate in Britain. There are hundreds and hundreds of websites detailing campaigns to stop local closures. The Countryside Alliance, the Lib Dems, the Scots and Welsh Nats, local newspapers, most Tories, most Trots and a score or more Labour MPs, all agitating to prevent their local office closing.

Few express themselves so elegantly and so revealingly as Deborah Devonshire, whose rural office and shop in Edensor, on the Chatsworth Estate, sold its last stamp last week. Her article fused feeling with argument and regret with anger. “No more the postmaster with one elbow on the counter,” she wrote, while also invoking the less literary image of having to use the car to shop at the Bakewell supermarket, and how awkward that would be for elderly non-drivers.

This is a recognisable theme: old folks unable to use services because they are too far away. More surprising was the duchess's revelation that the ancient cottage played the role of a social club where village people met to chat, exchange gardening tips and learn of the distant exploits of ex-villagers. “We all knew each other... Now our meeting place is dark and dead.” Though in fact it isn't, because the tearoom part of the Edensor business has survived, but - for some reason or other - the Duchess tells us that the local elderly prefer tea in their own houses. Fair enough.

Familiar too is the placing of the blame. “The Government doesn't care,” wrote Her Grace, and so “a vital support, impossible to value in money but sticking out a mile to those of us who live in villages, has gone.” That phrase “impossible to value in money” is, of course, a euphemism. What is really meant by it is that the activity in question loses perfectly measurable and usually huge amounts of dosh, but that it should nevertheless be subsidised because of its broader utility. And these sentiments, varied slightly according to location and author, are practically universal. A resource, possessing various almost metaphysical characteristics, is being destroyed by a mentality that is concerned only with profit. In rural areas the losers will be the elderly, in urban ones they will be the inner-city poor.

The irony is that the Government seems to agree with its own most vociferous critics. If Post Offices were run as a straightforward commercial operation like, say, Tesco, then only about 4,000 of the existing 14,000 or so offices would survive. The Post Office itself has calculated that the level of oversupply of facilities in the rural areas runs at between 65 per cent and 80 per cent, with only one tenth of opening hours in rural single-position branches being occupied by customer transactions. Yet the current closure plans still envisage 12,000 offices surviving, which will receive a subsidy (or “investment”) of £1.7 billion of taxpayer's money between last year and 2011. This, together with the closure programme, is being done to try to contain a loss that has been running at £4 million a week. And we have no real idea whether it will work.

So, in essence the Government is already letting parts of the post office system run as though they were social services; the campaigners are merely arguing that the handouts should be even greater. In the capital Ken Livingstone is promising to subsidise each of the 171 threatened London offices, if it becomes necessary. No one, absolutely no one, from one end of the spectrum to the other, seems to have the courage to call this spending into question. There is no counter-pressure on the Government whatsoever.

Yet at the heart of the post office problem is one simple fact. However much we may claim to “want” there to be post offices, we are increasingly unlikely to use them. They are an antique habit - a virtue, almost - which we are losing. I scarcely visit our local post office at all, and it doesn't take much to winkle out of “I use it all the time” protesters that, in fact, they vastly exaggerate their own attendance.

I am not saying that there aren't victims of change, people who, for reasons both voluntary and necessary, don't have bank accounts, don't shop at supermarkets and can't use the internet to make transactions or to fill in forms. It's always been true. Did you know that petrol stations have been closing at the rate of 600 per year? Are they not often a social hub? Deborah Devonshire informed her readers that there had been a post office at Edensor since 1886. But I couldn't resist discovering that the village's one pub had closed 16 years earlier, in 1870.

In the best old days, the 1900s, the duke and his house guests required a runner - a bell-boy - to take telegrams between the great house and the Edensor telegraph office. “It's all gone,” wrote the duchess, “There is no bell-boy and no Post Office. Now, that horrible form of communication, e-mail, rules... Bang go human relationships.” Is that what this is really about? Rural people don't use village shops, don't send their children to village schools and yet refuse to face up to their own responsibility for the inevitable closures, blaming the politicians. In the cities we do the same.

We got into our cars, shunned the trains, but loaded the opprobrium for own choices on the head of the infamous Dr Beeching. It was him, not us. Four million fewer of us use post offices this year compared with three years ago, but when it comes to the question “who killed the postmaster?” we all point at someone else.

Readers, we did it. We are guilty. I regret the passing of red phone boxes; but not enough to make a call from one. I lament the loss of human contact, and order food by Ocado. The Devonshires mourn the loss of the era of the telegram - and run one of the best websites I've ever seen.

Times Recommends

• You created the job. You should do it
• A swindler with a ready maid plan
• Charming to pillory disabled Brown