Philip Hensher: Is it a castle – or is it just a source of capital?

The mansion tax strikes hard at something close to the English heart. Houses are extensions of the self

The idea of trading the largely useless 50 per cent top rate of income tax for a "mansion tax" has some things to be said for it. Property prices have risen so rapidly in recent years, and so little of this rise has been used to public advantage. A mansion tax would ask for something from overseas speculators – it does seem right that the Russian oligarchs buying up massively expensive property in Britain and forcing up prices all round should contribute something to the public purse.

It's been argued that inequalities in wealth in Britain greatly exceed inequalities in income, an injustice which a tax on the value of property would begin to address. And there seems no doubt at all that property, even now, is insanely overvalued. Very ordinary one-bedroom flats in very ordinary parts of London are 10, 15 times an average London salary.

The "mansion tax" is quite misnamed. If the tax bites at property values of £1m, it will affect semi-detached Edwardian houses in Clapham. But the price of property needs to bear some kind of relationship to a normal income. No one can think houses of that sort are really worth 15 times a professor's salary. A mansion tax can't establish rational prices on its own, but it can act as some kind of brake on an out-of-control market.

The many good arguments in favour of a mansion tax, however, run up against a particular, and perhaps peculiar attitude towards property on the part of the British. It's not quite true that the British have a unique attachment to property ownership in Europe. Many of the former countries of the Eastern bloc now have a much higher ratio of owned property to rental. Nevertheless, historically, compared with our largest immediate neighbours in France and Germany, we have been much more likely to own our homes than rent them. A set of attitudes follow on.

These attitudes emerged very powerfully in responses to the proposed mansion tax. Rather than thinking about the immense profits that have accrued over the years if, say, you bought that Clapham semi for a few thousand pounds, people started to talk about the cruelty of making demands of people who were, in the phrase, property rich and income poor.

There are people, we are told, who now live in houses valuable beyond anything they could have anticipated, with the mortgage paid off but living on pensions of £30,000 or so. How are they to pay such a tax? Perhaps heartlessly, one thinks that if they are so worried about their income, they might as well sell the house and realise some of that vast windfall. But apparently that's not how things work.

What is property? Our attitude to it starts to resemble the attitudes of a previous generation towards capital, something which is just there like a duty, which may not on any account be drawn on. "Is it money?" a character in Ivy Compton-Burnett asks somewhere of capital. "It seems as if it might be", with the implication that, unreachable, it really is not money at all.

Property as the repository of savings which we have done nothing much to accumulate, and property as the guardian of our financial future, are two beliefs that have emerged in recent years. Another is a deep-rooted concern in English life for property as a sort of extension of our own selves. English novels have a tendency to revolve around houses, and always have – think of Mansfield Park, Wuthering Heights, Howards End, Brideshead Revisited, and onwards. We think of houses as embodiments of moral virtues and personal qualities. Do European novels work in quite the same way? The houses in Tolstoy, Proust or Mann are the houses of gentlemen or middling folk, in town or country, inherited or rented and that's the end of it. It is impossible to imagine them thinking up a house as peculiar as John Jarndyce's Bleak House. It just would not interest them.

The English attitude that their houses are the most efficiently observable extensions of their own selves, and an advertisement for their worldly accomplishments, has resulted in some peculiar situations in real life. Emma Harrison, a director for the recruitment company A4e, largely if not entirely funded by government money, finds herself in a position to buy a former teachers' training college, Thornbridge Hall in Derbyshire, to live in, and sees nothing odd or immodest in doing so. I well remember Thornbridge Hall when it was used for orchestra training courses by Sheffield council, and can't imagine anyone wanting to live in it. Even an Emma Harrison can fart in only one chair at a time, after all.

The point of it is, of course, to show off; to demonstrate how wonderful a person you are by going on about your property. Possibly the most vulgar conversation in the world is that conducted between English people in good times about the rising value of their houses, rapidly followed, in less good times, by that extraordinarily tedious and common conversation about the building work people are having done.

So the mansion tax strikes hard at something very close to the English heart. Money comes and money goes, but the second an Englishman gets hold of a heavily mortgaged fourth bedroom, that is his, and nobody else's business. Let anyone else try to put him in a position where he has to move on through lack of readies, and cries of injustice and unrighteousness ring out. Visions of poor widows being thrown out of their £2m stucco terrace and forced to move, in their twilight days, are conjured up to tug at the nation's heartstrings.

Really, it's only property. It's only a possession. It isn't your life: it only seems, sometimes, as if it might be. And even if it were, there are other lives to be had, in the windows of estate agents.