Today, the Mail publishes pictures of the latest squalid, tented encampment to spring up in Calais, housing hundreds of would-be illegal immigrants who have crossed deserts and oceans in the hope of sneaking into Britain.

Determined and desperate, these men, predominantly from Ethiopia and Eritrea, are prepared to risk death by jumping on to moving vehicles destined for the Channel Tunnel.

The Government does not have a clue how many make it – though only yesterday six illegals were found in Surrey, hidden on a lorry transporting luxury Maserati sports cars.

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Squalid: Would-be Eritrean and Ethiopian immigrant have crossed continents in the hope of living in Britain

What is certain, however, is that with the black economy booming, the number of illegals living here is certain to make a mockery of the last official estimate, from 2005, of 570,000 – this on top of the four million legal migrants who have settled here since 1998.

Yet, disturbingly, the man appointed by the Home Office to identify the gaping holes in our borders, chief inspector John Vine, yesterday quit after repeated Government meddling in the publication of his often devastating reports.

One investigation by him had 15 paragraphs redacted by the Home Secretary on ‘national security’ grounds, including the number of illegal migrants sneaking into Britain on Eurostar trains.

Other reports remain delayed – suggesting Whitehall is more interested in censoring bad news than getting a grip on the problem.

Then there is the Government’s confused response to legal immigration which, at current levels, will add an utterly unsustainable 20million to the population over the next 50 years.

The case for mass immigration has been demolished.

In a report published yesterday (and predictably ignored by the BBC) Cambridge academic Robert Rowthorn said the pressure on schools, housing and hospitals far outstrips any economic benefits of such historic levels of immigration.

Encampments: The men and women in the camps are prepared to risk death in their quest to sneak into the UK

Yet, in what had been billed as a major moment, all David Cameron unveiled this week was gimmicky tinkering on restricting the access of EU migrants to out-of-work benefits – ignoring the fact the vast majority come to work (with their wages topped up by generous tax credits, costing Britain billions every year).

As this paper argued on Wednesday, the Prime Minister should come clean that, under our present relationship with the EU, there is nothing he can do to stop the free movement of workers into Britain.

He could then turn this to his advantage by pointing out the only way to control immigration is to change this relationship – and only his party is offering a realistic hope of a referendum on our membership of the Brussels club.

The success of Ukip, which could cost the Tories the next election, demonstrates why Mr Cameron must urgently show his Government is treating the issue of mass immigration – legal and illegal – seriously.

So far we have little evidence of that.

End the secret arrests

First, police disgracefully kept secret the fact a key law and order adviser to the Prime Minister, Patrick Rock, had been arrested for possession of child porn.

Now, as we reveal today, it emerges officers similarly failed to disclose for six months that a senior official at the Cabinet Office had been arrested for the same grave offence.

Crucially, even when Sebastian Crump was charged, the Met did not disclose who he had worked for.

Kept quiet: Cabinet Office official Sebastian Crump, left, and Patrick Rock, right, an adviser to David Cameron, were both arrested on child porn charges without being identified

Yesterday, in a hugely significant judgment, the Appeal Court’s Lady Justice Sharp said there was no justification for the police not identifying a person at the point of arrest, since the public fully understand this does not mean they are guilty.