Leading article: Tread carefully, Mr Cameron

Of all the phrases that have come back to bite politicians – "read my lips", "purer than pure" – David Cameron's "we're all in this together" is near the top of the historic list in its potential for embarrassment. The reason that he and the Chancellor, George Osborne, use the slogan is that it touches a powerful part of the national psyche. Folk memory of collective sacrifice during the Second World War means that there is a willingness to accept hardship at a time of crisis, provided that everyone else bears their share.

That is why Mr Cameron's employment of a group of apparently party political image-makers as temporary civil servants is so dangerous to him. There is much more at stake here than a frankly academic dispute about the politicisation of the Civil Service. The whole of the Prime Minister's compassionate approach rests on the proposition that we are One Nation in adversity. It is a proposition to which The Independent on Sunday is sympathetic. We accept – as does Douglas Alexander, Labour's work and pensions spokesman, writing for the IoS today – that our welfare system needs to be reformed, and we welcome Iain Duncan Smith's attempt to improve work incentives. We think there is something in the idea of the Big Society; that, at the margins, there needs to be rebalancing in favour of personal responsibility and away from the assumption of state provision.

Yet there is a danger in all this that the burden of the spending cuts falls disproportionately on the poor, while ministerial rhetoric about fairness is attached to mere gestures. We felt, for example, that when Mr Cameron failed to mention bankers in his speech at the Tory conference, this might have been because he had some tough measures to curb corporate greed held back for last month's spending review. But no. All that Mr Osborne announced was the bank levy, a sensible measure but one that has nothing to do with burden-sharing by the well-paid; it had been devised as a form of insurance against a future credit implosion. That Gary Hoffman should show a sense of responsibility and renounce his £500,000 pay-off as chief executive of Northern Rock is admirable, but not enough to get the Government off the hook of business-as-usual in the rest of the overpaid City. Last week's more typical example was Antonio Horta-Osorio's move from Santander to Lloyds, for £8m a year.

It is against this background that Ed Miliband in the House of Commons last week raised the employment by No 10 of Mr Cameron's personal photographer from his days in opposition. The Prime Minister was dismissive, accusing the Labour leader of failing to "engage in the substance about the future of our country". This was wilfully to miss the point. It is not the scale of the issue – putting a handful of people on the civil-service payroll – but the principle. When the Prime Minister is making decisions about public spending that will cause hardship for people on low incomes, this shows a poor sense of priorities. It looks as if the fabled Cameron touch, at ease with people of all backgrounds despite his own fortunate upbringing, has failed.

Mr Cameron was once so righteous about the Labour government's employment of special advisers, but this looks like a hypocritical attempt to avoid employing too many explicitly political advisers himself. It was telling that one of the defences offered by No 10 was that the Conservative Party had offered to pay these salaries, but had been overruled by mandarins – which rather suggests the Tories thought they were political appointments.

Voters may detect insincerity. Mr Cameron has sometimes said one thing in opposition and another in government. On Burma, for example, when he was posing as a champion of human rights, in an article for this newspaper in June 2008 he urged China to put pressure on the regime, and said that the generals "could end up answering for their actions before the International Criminal Court". We shall see if he is so robust on his visit to China this week, in the wake of the news that Chinese artist Ai Weiwei, whose Sunflower Seeds has just opened at Tate Modern, is under house arrest, and in his response if there is obvious fraud in the Burmese election or if the junta fails to release Aung San Suu Kyi.

The risk now therefore, both domestically and globally, is that the bigger prize – of mobilising a common purpose – could be lost. Then slogans such as "we are all in this together" would sound horribly hollow.