Anatomy of a Blair babe's downfall

When Bob Ainsworth, then a junior Home Office Minister, took a trip to Romania and Bulgaria in February last year, he could never have imagined it would end in a resignation that shook the Government.

It was during his routine visit to the capitals of the two nations that he first became aware of the serious claims of widespread abuse of the immigration system, with diplomats complaining that their efforts to stop various rackets had been thwarted by the Home Office's Immigration and Nationality Department.

Our men in Bucharest and Sofia were "demoralised" that their recommendations warnings about fraudulent applications had been routinely overturned once the cases were assessed back in the UK. Mr Ainsworth was told that there had been a "weakening ... of immigration control".

In his letter dated 4 March last year, the junior minister did his duty and reported the allegations to Beverley Hughes. Ms Hughes wrote back twice to confirm action would be taken, on 17 March and again on 10

April. The whole issue may well have been buried and forgotten but for the decision of James Cameron, the consul in Bucharest, to email David Davis, the shadow home secretary, with his concerns that migrants were being let into the country unlawfully.

When the accusations emerged, Ms Hughes was bullish about her own position, privately telling friends that she would not be dragged down over the issue. But it was precisely that over-confidence that appears to have led to her downfall when she appeared on BBC2's Newsnight on Monday to put her case. She had no knowledge of the scams raised by Mr Cameron, she said.

Mr Ainsworth realised there was a real risk that Ms Hughes was giving a misleading impression. Now in his new role as deputy chief whip, he knew more than most the need to be utterly transparent and decided to ring her to remind her of his own letter. Whenever a minister is under fire, a cry goes up in Whitehall for an urgent paper trail to be conducted and it remains to be seen whether it was Mr Ainsworth's call alone that led his letter to be unearthed.

Once Ms Hughes found the letter, she knew her position was untenable. After a particularly bruising Prime Minister's Questions yesterday, Ms Hughes and Home Secretary David Blunkett saw Tony Blair in secret to reveal the potentially lethal contradiction between her statements to Newsnight and the letter .

There is already a long list of ministerial resignations from this Labour administration - Peter Mandelson (twice), Stephen Byers, Estelle Morris, Alan Milburn, Geoffrey-Robinson and Ron Davies. But what sets Ms Hughes's departure apart is that this is the first time that the Tories have actively played a crucial part.

But her decision to step down is all the more toxic for this Government because it crystallises so many of the issues that threaten to undermine it. Trust, or the lack of it, is already hard-wired into the public's image of the Blair leadership.

Immigration and asylum are emerging as the number one grievance of the voters. Incompetence by varying Whitehall departments is undermining the huge amounts of cash spent on public services. Dissent from whistleblowers has capped an image of a Government that has finally fallen out of love with its civil servants. Ms Hughes's resignation also cruelly exposes the limits of Blunkett's frequent plea for a mature approach to the individual responsibilities of ministers and their civil servants. Mr Blunkett claims that politicians in the modern age have responsibility without power because they cannot possibly control every policy. But today's events show that ministers cannot dodge blame when they are not just involved but are found to have obscured their involvement.

Ms Hughes's scalp will almost certainly be credited to Mr Davis, who won the approval of Michael Howard last month to mount a vigorous campaign calling for her sacking. Some Tories are extremely wary of devaluing the currency of the resignation call. But once Mr Davis received his email from Mr Cameron, a decision was made to really go for Ms Hughes.

Given that the Conservatives have finally discovered New Labour's former gift for "drip-drip" news management, and that civil servants are so disgruntled that they are prepared to leak, there are sure to be further details.

During the last years of John Major's floundering administration, calling for ministerial resignations became a regular contact sport for Labour shadow ministers keen to make their name. Tony Blair regularly led the way. The problem now is that the Home Secretary is clearly vulnerable. If he misled Parliament about his knowledge of any warning sent to Ms Hughes about the Romanian scams, he will be staring down the barrel of his own departure from Government.

At that point, the Prime Minister himself will be in grave danger, not just of losing trust but high office.