Today's report on immigration from the House of Lords Economic Committee strikes a devastating blow against years of blatant government propaganda. It rejects outright the Government's argument that a high level of immigration is of economic benefit to the UK.
This is exactly what we in Migrationwatch have been saying for at least three years in the teeth of opposition and, indeed, insults from the immigration lobby.
Now, at last, after the first major inquiry of its kind in this country, our view has been endorsed by the considered verdict of one of the most heavyweight committees of Parliament, including, as it does, two former Chancellors, a former Governor of the Bank of England, and several distinguished economists as well as captains of industry and finance.
The committee's findings are devastating. The report takes each of the arguments that the Government has been putting forward for years, and tears them to shreds one by one. It is a watershed in the debate on immigration.
Most pertinently, the Government's key claim that immigration increases Britain's overall gross domestic product (GDP) is dismissed as "irrelevant and misleading" - even though, as the report points out, it is a claim that has been "persistently emphasised".
Far from focusing on GDP, the report says, the real issue is whether immigration has boosted income per head of population; and concludes that the effects on per capita income are "very small, whether positive or negative".
So if the Government's principal argument in favour of unprecedented immigration - namely that it has made us individually richer - is found to be disingenuous, how can it justify the extra 2.5 million immigrants it has permitted to enter Britain on its watch? Particularly in the light of the all-too-evident strains on public services that this influx has caused.
It is no good repeating yet again the Government's claim that immigration has contributed £2.5billion to the Exchequer, for this too is questioned. The report concludes that the impact on the Exchequer "is likely to be small".
And what of the Government's argument that immigration is needed to fill job vacancies? Such claims, the committee judges with admirable restraint, are "analytically weak". Immigration, it continues, is unlikely to be an effective tool for reducing vacancies other than in the short term.
In fact the employment statistics prove the committee's point beyond doubt. It is some five years since the Government started to argue there were 600,000 vacancies that needed to be filled by immigration. In that time, we have had net foreign immigration into Britain of nearly one-and-a-half million and guess how many vacancies we still have - 600,000!
The reason, as the report points out, is that immigrants fill some vacancies but their extra demand for services and goods creates others. The Government's argument on job vacancies would, therefore, lead to a continuous cycle of immigration.
How about the Government's claim that, because we are an ageing population, we need immigrants to provide the wealth that will pay our pensions?
This, too, is dismissed with contempt. It "does not stand up to scrutiny," says the report, for a reason that should be obvious to the Government: namely that immigrants themselves grow old and draw pensions.
The way to tackle pensions, the committee suggests, is not unlimited immigration but an increase in the retirement age.
In last-minute evidence to the committee, the Government stressed the "dynamic" economic benefits from having a more diverse society. This sounds plausible in theory, says the report, but there is no empirical evidence.
Taking the report as a whole, it is hard to imagine a more comprehensive demolition of the Government's case for massive levels of immigration - a policy pursued in the face of deep public concern.
Why then has it taken so long to blow these false government claims out of the water?
Part of the answer lies in a widespread reluctance even to discuss immigration.
A recent Newsnight poll of white British adults found that 77 per cent felt that they could not criticise immigration without being labelled racist. Times are now changing, thank goodness, but the multicultural enthusiasts have had it all their own way for far too long.
Why has the Government continued to pursue its immigration policy when it must have known that it was deeply flawed?
Some ministers may have believed their own propaganda on multiculturalism. Others, notably Gordon Brown at the Treasury, were keen to see impressive economic growth figures (yes, Britain's GDP does improve with increased immigration but, as the committee itself pointed out, not income per head). And, of course, it helps to keep inflation down to have a ready supply of cheap labour from overseas.
Furthermore, the importation of skills covered up the Government's own failures over the education and training of Britain's workforce.
One has to ask, too, whether there could be a political aspect. Immigrant communities are predominantly Labour voters. If they had all been budding Conservatives, one wonders whether the situation would have been allowed to continue for so long.
There is one more question raised by this report. Where was our supposedly independent Civil Service while the Government's misleading claims were being repeatedly trotted out? Political aspects are not matters for the Civil Service, but it does seem to have been complicit in the output of misleading information over a period of some years.
Here, I think, one can detect the malign influence of political advisers who have undermined both the independence and the self-confidence of the Civil Service. In the past, it has not always paid to stand up to government ministers; it certainly doesn't pay to do so now.
Set on its political course of increased immigration, all seemed to go swimmingly for the Government as it trebled the number of work permits and later lifted all restrictions on the entry of East European workers.
Then the politics started to fall apart as the white working class, which felt threatened by immigrants prepared to accept lower wages, began to desert Labour, often for the BNP - a development largely explained by the same Newsnight poll which found that 58 per cent of the white working class felt that "nobody speaks out for people like me in Britain today".
The Government is now in a serious bind. Its traditional supporters are deserting, 80 per cent of the public disbelieves it on immigration and, with this report, its underlying justification is in ruins.
We should not be misled by the Government's claims to be introducing the most far-reaching immigration reforms for a generation. Having lost control of our borders (and allowed the asylum system to collapse into chaos), the Government's response so far has been to form two more committees to assess the economic 'need' for, and the social impacts of, immigration.
This will not remotely restore confidence. It does not address the real issue which, as the report says, is how much net immigration is desirable. The committee calls for an explicit and reasoned indicative target around which immigration policies can be adjusted, but this is something the Government seems unable to address, perhaps for ideological reasons.
What we need is not more committees but a clear shift of policy towards the concept of "balanced migration" between immigration and emigration. Setting this as the key objective would provide a sensible way forward for a public increasingly desperate for practical solutions to a developing crisis.
Sir Andrew Green is a former British Ambassador to Saudi Arabia and Syria.
© Copyright of Sir Andrew Green