TRUTH is important in politics. Never more so than today, when huge issues are at stake affecting the lives of every voter and the future of the nation and the world.

Political deceit is a form of theft. When people or businesses get money by deceit they face criminal charges. When politicians win power by deceit they can do vastly more harm, but face no penalty at all.

Our rulers expect us to comply with their laws and decrees, to pay the taxes they devise, to make the sacrifices they exhort on us, even sometimes to die in war.

In a democratic society, such obedience has to be earned. When our rulers use lies and misrepresentation they fray the bonds of loyalty we owe to the state.

Our rulers also ask us constantly to resist extremism from any part of the political or social spectrum. But when our rulers themselves peddle falsehood and fantasy they are no better than the extremists. They make any kind of extremism more plausible.

That is why it is vital to expose lying politicians.

Many disagree. They believe that it is in the nature of politicians to dissimulate and lie. They say that it is as futile to complain about this as to complain that wasps sting.

My answer is simple. Yes, it is true that politicians lie and cheat regularly. Yes, the culture of political lying and cheating has grown deeper and more pervasive. But that is no reason to let politicians get away with it.

Least of all Boris Johnson, who is uniquely deceitful among British prime ministers. I make this statement with authority having been a political correspondent for approaching 30 years.

In a short time, Mr Johnson and his ministers have set new standards. They tell untruths at a faster rate than the governments of Theresa May, David Cameron and Gordon Brown.

Even more than the Tony Blair government. And I was so appalled by the dishonesty of Mr Blair’s administration that I wrote a treatise, The Rise of Political Lying, on the subject.

Since then I have kept a dossier of political lies by British governments. This dossier suggests that the scale of political lying since Mr Johnson became prime minister has risen exponentially.

That’s why I decided to compile and publish this dossier of the lies, falsehoods, and misleading statements made by Mr Johnson and his colleagues.

We knew the prime minister already had a long record of mendacity and deceit when he entered Downing Street. As a young journalist, he was sacked from The Times (which later endorsed his Tory leadership campaign) for fabricating a quotation.

He was later sacked by Tory leader Michael Howard after dismissing accurate reports of his infidelity as an “inverted pyramid of piffle”. In a senior role in the Vote Leave campaign he made repeated misleading claims about the benefits of Brexit.

Since entering Downing Street, Mr Johnson — as my dossier proves — tells fibs about almost everything.

Some are relatively unimportant. Even this displays an attitude that the truth simply does not matter. All that counts is what the government wants people to believe at any one time.

But Mr Johnson and his ministers have also made misleading statements about important matters of state. About the boost to government spending at the heart of the Johnson domestic agenda. About the prorogation of parliament. Most important of all are the series of false and misleading statements about Brexit.

Within the term lying I include any statement deliberately intended to make its audience believe something which is less than the whole truth. It may be a statement known to be false at the time it was made. But it may also include statements which rely on partial or selective facts and those based on false inferences and interpretations.

Politicians — like people in any other walk of life — may make false statements in good faith. But it is then their duty to correct or retract a false statement the moment they know it to be inaccurate. If they continue to rely on it they turn it into a lie.

For example, Mr Johnson continually claimed in the referendum campaign that Brexit would generate an extra £350 million each week for the NHS.

When he first made this claim he may have genuinely believed it. But he went on making it long after it had been debunked.

When the prime minister or any of his ministers have uttered something they ought to have known was untrue , I say so explicitly — and call them liars.

Lesser offences of selective presentation will go into a less serious category of misrepresentation or falsehood.

I have gone to great lengths to make sure that this dossier will be accurate, fair, and balanced. All claims are hyperlinked to the source material. If I make mistakes, I will correct them as soon as they are brought to my attention and I will make clear I have prominently corrected them on the website. Equally, readers of this website are encouraged to contact me with fresh lies or false representations from Mr Johnson and his government at this address. I will then sift, check and verify them before publication.

Peter Oborne