It may be hard to believe it now, but there was a strange time in 2012 when it seemed that the party leaders were about to publish their income-tax returns. Boris Johnson, then running for re-election as Mayor of London, agreed to publish his accounts, which showed that he paid about 40 per cent in tax on £1.7m of earnings over the previous four years. His opponent, Ken Livingstone, was embarrassed to reveal that he had been paid through a company, a device that could have reduced his tax bill.

David Cameron said he was “relaxed” about publishing his tax return; Nick Clegg said the public had a right to know about his finances; Ed Miliband said he was happy to publish his. It seemed as if it were simply a matter of the Prime Minister finding his password for the HMRC self-assessment website and printing the document.

Strangely, this commitment to greater openness came to nothing. It turned out that “relaxed” meant “absolutely the last thing I would ever do”. When he said he believed “the time is coming” for politicians to be more open about their personal finances, he meant “the time will always be coming”. Without Mr Cameron ever explicitly saying no, his tax return saw no light of day before the election in May this year. Nor did Mr Clegg’s or Mr Miliband’s.

This is a small example of a larger truth: that most politicians say they are committed to openness but do not mean it. We should be annoyed but not surprised, therefore, that the Government is trying to retreat from its promises on transparency. As we report, no department has published its quarterly report of ministerial meetings, gifts, hospitality and overseas travel since March, three quarters ago.

This looks like a deliberate attempt to shelve a commitment given by Mr Cameron shortly after he became Prime Minister in 2010.

As Tom Watson, the Labour deputy leader, says, these quarterly updates are essential “to ensure we know who is influencing government policy”. Yes, they take up valuable civil service time and politicians find them tiresome if they give rise to media flurries that they think are unjustified. But that is how we keep our democracy honest.

It is not as if this were an isolated example. The annual list of special advisers and their salaries – salaries paid for from public funds for political appointees – published on 30 November last year is now two weeks late. In itself, that may not seem so important, but Government press offices use the non-publication of the list as a reason to refuse to answer any questions about special advisers. It was only through journalistic endeavour that this newspaper established recently that the Chancellor of the Exchequer employs 10 special advisers – five times as many as the normal limit for a cabinet minister.

The review of the powers of the House of Lords being carried out by Lord Strathclyde, the former leader of the Conservative peers, seems designed to weaken the Upper House’s scrutiny of legislation.

Then there is the Government’s review of Freedom of Information (FOI) law, which ought to be about extending its scope to other bodies that carry out public functions, but seems instead to be intended to make it harder for citizens, directly or through journalists, to hold the government to account. Tony Blair colourfully chastised himself in his memoir as a “nincompoop” for having brought in the FOI Act. But it is precisely because the powerful find openness irritating and inconvenient that the rules need to be kept up to the mark.

Politicians will always pretend to go along with openness, and to be “relaxed” about it. But they will always be trying to keep information to themselves if they can. They must not be allowed to get away with it.