WE HAVE come to expect, over the years, that politicians will be economical with the truth during election campaigns. That phrase, you might recall, was coined by Sir Robert Armstrong, the Cabinet Secretary during the infamous Spycatcher trial, in which the government of the day sought to suppress the publication of a book by a former MI5 employee. But it had its origins in a phrase used by the 18th-century father of conservatism, Edmund Burke. The developing etymology of the idea is a revealing one.

In Burke’s day, “economy of truth” seemed to indicate not much more than the withholding of information. Mark Twain added a dimension of irony, a century later, when he observed: “Truth is the most valuable thing we have. Let us economise it.” Sir Robert went further with a definition. Being “economical with the truth” was to convey “a misleading impression, not a lie”. Politics has moved a long way since then.

“Economy of truth” gave way, first, to a cavalier attitude towards facts. The Culture Secretary, Nicky Morgan, offered a pretty standard example of that this week when she tried to wriggle out of the fact that 19,000 of the extra 50,000 nurses that the Conservatives have promised turn out to be merely existing nurses who will be persuaded not to leave. It was much like the promise of 40 new hospitals, when funding for only six was in place. Or the 20,000 extra police — without mentioning the 21,000 officers axed during nine years of Tory austerity.

When the Conservative manifesto was published this week, Boris Johnson’s promise to cut taxes for higher earners had vanished. So had the “clear plan we have prepared” to “fix the crisis in social care once and for all”. Cuts to National Insurance, it emerged, would amount an extra £85 a year — not the £500 that he had originally announced.

Such sloppiness is bad enough. But the Conservative Party has gone further, slipping into systemic deceit. A video of the Shadow Brexit Secretary, Sir Keir Starmer, was doctored to make it look as if he could not answer a question that he had answered decisively. The Tory press office Twitter account was disguised to look like an independent Fact Checker. Even after the Prime Minister was laughed at to his face by a television audience — when he was asked “Does the truth matter in this election?” — the disinformation continued. The Tories set up a fake “Labour manifesto” website and paid Google to promote it to voters who were looking for the real manifesto.

Labour has different problems, with its fantasy economics and accusations of anti-Semitism that just will not go away. But there is a difference between self-delusion and wilful deceit. Disillusioned Tories such as David Gauke have spoken of a “win-at-all-costs” culture now existing in the Conservative Party. It was Dominic Cummings’ “Vote Leave culture we saw in 2016”, he said.

You would have thought that no self-respecting political party would need to impersonate others to put its campaign messages out. Clearly not. The time may have come when we need an independent election ombudsman to police and penalise our political parties. It is hard to see how we can leave it to the current crop of politicians to restore trust in our political system.