How can you tell when politicians are lying? Their lips are moving. It's a hoary old joke but it can still be guaranteed to raise a rueful chuckle among British voters increasingly disillusioned with the political process. I always thought it a tad unfair.

Yes, politicians do deploy all manner of contrivances to avoid telling the truth when it's inconvenient. As someone who's spent an adult lifetime interviewing them, I can readily testify to that.

They regularly mislead, dissemble, obfuscate, bluster, sidestep the question and teeter on the edge of lying by being economical with the truth.

But outright lie? I have found that to be very rare indeed – on either side of the political divide.

No longer. I have had to revise my opinion. In the so far short and sad existence of the Starmer Government, lying has become not just a feature to which it increasingly resorts – it's become its modus operandi, with the Prime Minister himself leading the charge into untruths.

For me, matters came to a head this week.

In the wake of the latest net migration figures, showing a 50 per cent reduction compared with 2023, the Home Office tweeted out a poster which said 'Net Migration cut by nearly 50%', describing it as 'the largest-ever drop in net migration for any 12-month period'.

The implication was clear: it was all somehow a result of Labour Government policy. But, of course, it wasn't. And the Government knows it wasn't.

Starmer realised that what had made him Labour leader wouldn't necessarily make him Prime Minister. So he fought last year's election with a manifesto as phoney as the one with which he'd bid for his party's leadership, writes Neil

Last year's fall in net migration (only the 'largest-ever drop' because it was coming off such a high total the year before of almost one million) was largely the result of tougher visa rules introduced, belatedly, by the previous Tory government when James Cleverly was Home Secretary.

For half of last year Labour wasn't even in power. In opposition, it had actually attacked Cleverly's rule-tightening, with then shadow Home Secretary Yvette Cooper (now in charge of the Home Office) dismissing it as 'chaotic' and 'Tory failure'.

But that didn't stop Keir Starmer from going even further than his Home Secretary. On Thursday he tweeted out the claim that 'we have nearly halved net migration in the last year. We're taking back control.'

Labour, of course, had done no such thing. It had merely presided over implementing the new rules it inherited from the Tories – rules it had criticised in opposition – when it took power in the second half of the year.

This is not misleading or obfuscation or being economical with the truth or any other circumlocution we might like to fall back on to gloss over what is really happening. It is, in plain English, a downright lie.

Why? That's easy to answer. The Government's approval ratings are in the dirt. So are the PM's personal ratings. As the economy stutters during the year ahead, there's probably worse to come.

Nigel Farage's Reform Party is soaring ahead in the polls, leaving Labour in its tracks and the hapless Tories nowhere to be seen.

Uncontrolled mass migration is the rocket fuel that propels Reform. Labour is so desperate to counter its appeal that it's ready to lie about the issue which gives Reform most salience. It's a response born out of panic. And it is, of course, fooling nobody.

This week I asked a prominent Labour MP, often wheeeled out for broadcast interviews, to tell us exactly what Labour had done last year to cut net migration by 50 per cent. I said I was especially interested in what Labour had done during the six months it wasn't even in power! Naturally, I'm still waiting for an answer.

'You really must take us for fools,' I said.

Perhaps we should not be surprised that lying and gaslighting – telling us things we know not to be true but doing it with such authority that we begin to question our own sanity – have become the distinguishing features of the Starmer Government.

The Prime Minister, after all, has a long track record of doing both.

Let us not forget that Starmer was elected leader of the Labour Party just over five years ago on an undiluted Corbynista prospectus. He proposed the nationalisation of energy, water and the mail, the scrapping of Universal Credit and university tuition fees, and banning outsourcing in the public sector.

He had once described Jeremy Corbyn as a 'friend' and then, sometime later, as 'never a friend'.

In a BBC TV interview to which many still refer, I asked him if he promised Corbyn's policies would be in the next Labour manifesto. His answer was a categorical 'Yes' – adding these policies were not just promises, they were pledges. Within a year every one had been junked.

Starmer realised that what had made him Labour leader wouldn't necessarily make him Prime Minister. So he fought last year's general election with a manifesto as phoney as the one with which he'd bid for his party's leadership.

'We don't need higher taxes,' shadow chancellor Rachel Reeves insisted during the campaign. Labour has 'no plans to increase any taxes', she regularly repeated (bar a few small, specific rises, like VAT on school fees), thereby confirming the old maxim that when a politician says they have 'no plans' to do something, the reality is they have a shed load just waiting to be wheeled out.

And so it transpired. Labour fought the election on tax rises of only £8.5 billion, an extra £9.5 billion in spending and £3.5 billion in additional borrowing.

In her first Budget last October Chancellor Reeves raised taxes by £40 billion and borrowed £36 billion more, allowing for a massive extra increase in public spending of £76 billion between now and the end of the decade.

So, an actual £76 billion more versus a promise of only a frugal £9.5 billion more.

I guess if you're going to lie you might as well make it a whopper.

Reeves claimed she'd been forced to increase taxes because she'd discovered a £22 billion 'black hole' in the public finances on taking office. But this was to pile lie upon lie.

As The Guardian revealed during the election campaign, it was always the plan to say, 'We've seen the books, it's much worse than we thought', as the precursor to whacking up taxes, spending and borrowing.

No doubt lots of documents and policy papers since last summer have been shredded and deleted at Labour Party HQ. But, one day, written evidence will come out to confirm what Labour intended all along. It always does.

At no stage has the Office for Budget Responsibility, which Reeves professes to revere, ever endorsed the existence of a £22 billion black hole.

What we do know is that the public finances, not left in any great shape by the Tories, were immediately made worse on Labour taking office by doling out all manner of inflationary pay rises to the party's friends in the public sector.

In any case, even if there had been a black hole of some £22 billion, when did that require £40 billion more in taxes and almost as much in extra borrowing?

In many ways the Starmer Government has never recovered from Reeves's disastrous first Budget – which has only made the PM even more cavalier with the facts. Labour had inherited 11 per cent interest rates, he told the House of Commons earlier this year. Which is odd since rates peaked at 5.25 per cent under the previous government.

Hospices have been given an extra £100 million to help them cope with the increase in employer national insurance contributions (NICs) imposed by his Government, he regularly tells the House.

He continues to claim this even after being told the £100 million is a capital grant and nothing to do with meeting running costs, such as increased NICs.

He boasts about an £880 million increase in funding for social care without mentioning the rise in NICs will cost care homes £900 million.

The lies and gaslighting are now coming thick and fast from the Starmer Government across a broad front.

Reeves continues to insist her Budget was tough but 'fixed the foundations of the economy', even as inflation spikes back to 3.5 per cent, dole queues lengthen and Government borrowing remains elevated – so much so that those lending the Government money are demanding record returns (higher than even during the ClusterTruss interregnum in 2022).

In reality, our economic foundations are shakier than ever, as we will discover when Reeves is forced to put up taxes again in her second Budget this autumn.

The Chancellor denies she'll have to do this, which pretty much guarantees that she will. Her promises of no more tax rises are as bankable as the ones she gave us during last summer's election campaign.

Sometimes the porky pies are too ludicrous to take seriously. Cabinet minister Lucy Powell claimed that if the Government had not cut the winter fuel allowance for most pensioners there would have been 'a run on the pound'. In which case, better sell your sterling fast now the Government is U-turning on the cut.

This week, Justice Secretary Shabana Mahmood, trying to deflect from her plans to let prisoners, even violent ones, out early, mooted the idea she might support mandatory chemical castration for sex offenders.

Her idea was to convince us that she wasn't quite the softie when it comes to penal policy that she seemed. It is, of course, an absurd proposition which will never happen. But it is gaslighting of a high order.

Increasingly, we're being misled by omission. Starmer boasts of his new youth mobility scheme with the European Union (which he ruled out only eight months ago – 'no plans', again).

But he cannot tell us how many will come here, for how long and what the division will be between work and study.

He says he's negotiated a better deal for British food and defence exports to the EU. But will not say how much the improved access is going to cost us (likely hundreds of millions) – or why we're paying for more free trade.

He claims to have opened the e-gates for us at European airports, without telling us when (not in time for this summer).

In all these cases we know what we're giving away (for example, fishing rights for another 12 years). But we have only the vaguest idea what we're getting in return. It's a pretty good rule of thumb that when governments won't tell you things it's because the truth will hurt.

That explains the mountain of obfuscation surrounding the Chagos Islands deal. The untruths we've been served up on that would merit an essay in their own right. Suffice to say almost everything we've been told, from the need to do the deal to the cost (the sums must have been done by Diane Abbott), is untrue – which makes it the perfect poster child for this Government.

In opposition, Starmer vowed to provide a Government in which 'truth means something and where honesty is at the heart of everything that it does… honesty and integrity matter. You will always get that from me.'

How hollow these words sound now from a man leading a Government which after less than a year in power is already a stranger to the truth.

The country has had untrustworthy governments in the past, from Harold Wilson's Labour administrations of the 1960s and 70s to Boris Johnson's government at the start of this decade. Whatever their achievements, it was always wise to perform an independent audit of everything they said.

But in 55 years of covering politics close up, I have never felt it necessary to accuse any government, on the Left or the Right, of congenitally telling untruths.

Now, for the first time, I do. The Starmer Government has taken the lying, the gaslighting and the deceit to a new level.

It has become endemic in almost everything it does – and it's getting worse. It corrodes public trust which, once lost, is impossible to rebuild.

Starmer is heading down a dark road from which, as he will soon discover, there is no return.