Opposition sometimes involves being seen to oppose your own instincts as well as the incumbent administration. That may be the best explanation for George Osborne’s determination, in his interview with The Times today, to minimise any prospect of the Conservatives adopting a radical tax-cut agenda. On the surface, he has all but dismissed the notion of pledging tax cuts on the basis that “the public finances cannot sustain that”. Deeper down, matters may be more complex.

Tax is a three-letter word that seems to have acquired the taboo status that four-letter words had until recently. A politician who promises a tax cut long before achieving office places himself in front of a number of high obstacles. The public, misled on tax by the winning party in the 1992 and 1997 elections, is disinclined to think that any future pledge will be honoured. Once a taxation policy is unveiled, ministers will take to the airwaves to demand that the spending “ cuts” necessary to finance it are spelt out and, regardless of what the details might be, insist that the price of even the most modest tax reduction would be the slaughter of the public services.

Mr Osborne must, however, make a clearer case for individual initiative and the virtues of the market economy. Promising a hefty tax cut is not necessary, but imposing discipline on state spending is an imperative.

On this, as many other subjects, the Shadow Cabinet has decided that there must be no hostages to fortune. The real debate in Tory circles is whether the party should be ready to unveil a precise position on tax much closer to polling day or keep it vague until power has been secured and then look closely at cutting taxes.

Both strategies involve risks. If the Tories outline their plans late in the day, they will not have time to make the case for a freer economy. But if they are too ambiguous in their intentions, many voters might not be inspired to turn out for them at all; or others, surprisingly the Liberal Democrats, could seize the headlines by putting forward proposals for reducing the basic rate of income tax and lowering the threshold at which the top rate is levied. Mr Osborne might assert confidently today that the tax cutters in his party will be “very disappointed”. They will not be going away quietly.

That is because while tax may be a taboo subject to political elites, it is not a question without interest to the electorate. Overall tax levels are high by historical standards and while there is a formula for reducing public spending as a proportion of national income over the rest of the decade, the Treasury has not indicated that relief will be forthcoming to taxpayers. Voters are indeed reluctant to believe that politicians will reduce the tax burden. Yet they would still like that to happen.

Intelligent members of the Cabinet already want Labour to move on this issue. It is obvious to them that those on £20,000-£30,000 a year, in particular, have grounds for resenting the amount of tax and number of taxes to which they are exposed. There are arguments as to the best means to rectify this situation — cutting tax rates, increasing thresholds, reducing council tax — but the perception that the status quo is not an appealing option is advancing. Mr Osborne will have to calculate when he should align himself with that sentiment openly. Tax may be a forbidden three-letter word now, but it will be common parlance come the next election campaign.