They have one ministerial scalp. And now they want Blunkett

The Tories are not going to stop with Beverley Hughes. They've tasted blood over the immigration debacle and they want more. For all Tony Blair's insistence that there is no crisis, and he has taken personal charge, this will be of little comfort to his Home Secretary.Francis Elliott tells the inside story of a turbulent week, while opposite, Mr Blunkett's shadow makes the case for a full inquiry

Beverley Hughes was never one of Tony Blair's most high-profile ministers. The 54-year-old former council leader was a middle-ranking administrator with a difficult and unglamorous job. Yet her resignation last week was among the most dramatic so far suffered by this Government.

The potential fallout is huge. It has thrown into doubt David Blunkett's political future as Tony Blair takes charge of a situation which, he admits, has eroded confidence in Britain's immigration system.

With the Tories and Liberal Democrats stepping up their demands for an independent inquiry, the Home Secretary now faces a series of awkward questions about what he knew of concerns at the front-line.

Ms Hughes' unwelcome emergence into the public glare began a month ago when a junior immigration officer went public with claims that visa checks were being relaxed on applicants from eastern European countries. The claims by Steve Moxon, who worked at the Sheffield offices of the Immigration and Nationality Directorate, were at first dismissed out of hand.

But by 7 March, Ms Hughes was under enough pressure to announce an internal inquiry into his allegations. Two weeks later, a jubilant John Prescott, the Deputy Prime Minister, told the Cabinet that the inquiry had cleared Ms Hughes of any improper conduct. The Home Secretary also spoke up for his junior minister and personal friend at the meeting, chaired by Mr Prescott as Tony Blair visited Libya. "David and John were passionate in their support for her. The feeling was she shouldn't be sacrificed to the Tories," said one minister.

The campaign against Ms Hughes was making Downing Street uneasy, however. Philip Gould, Mr Blair's pollster, has been growing increasingly alarmed by Labour's figures on immigration and asylum. The latest polls, shown to the election-planning group last week, show a dramatic month-on-month fall, according to one aide.

Downing Street, it turns out was right to fret, for even as Ms Hughes celebrated her acquittal, David Davis, the shadow Home Secretary, was moving in for the kill. For weeks he had had an email from a disgruntled civil servant warning that the abuses, first reported in Sheffield, were widespread and that repeated warnings from officials had been routinely ignored. Mr Davis, however, did not know who had written it.

The suspension of James Cameron, British consul in Bucharest, at once exposed and further disaffected Mr Davis's mole. Barely able to believe his luck, he contacted Mr Cameron and persuaded him to hand over documents proving that he and his opposite number in Bulgaria had repeatedly warned senior managers at the Immigration and Nationality Directorate of a well-organised criminal scam.

By last Monday, the shadow Home Secretary was ready to deliver his torpedo. It was a politically devastating critique from the front line.

Mr Cameron said that consul staff in Romania had watched helplessly as quite obvious frauds were being carried out, including the successful application of a one-legged man to work in Britain as a roofing tiler. The now famous Newsnight interview broadcast on Monday night that provides the officially sanctioned reason for Ms Hughes' departure included her claim that "we haven't had these allegations put to us before today".

Watching the interview, Bob Ainsworth, the deputy chief whip and former Home Office minister, winced. With MPs filing through the Commons lobby to vote on the Employment Relations Bill, Mr Ainsworth saw his former colleague and beckoned her to one side for a private chat. "He basically said that when she went through the papers she would see that he had sent her a letter on the worries of consul staff in Romania but she didn't see the significance then," a friend of Ms Hughes said last night.

One of the most awkward questions facing Mr Blunkett this weekend is whether the Ainsworth letter detailing the allegation to Ms Hughes, dated 4 March 2003, was, as is routine, copied to the Home Secretary. If so, Mr Blunkett will have to explain why he said on BBC Radio 4'sToday programme on Tuesday that he, too, was "not aware" of Mr Cameron's allegations.

It was at the La Poule au Pot restaurant in Pimlico, London, that evening that Ms Hughes is supposed to have first told her boss about the fatal paper trail from Mr Ainsworth that proved she had been made aware of visa scams in Romania and Bulgaria.

Mr Blunkett had taken her out to celebrate her birthday and her defiant performance in the House of Commons. "I am neither incompetent nor dishonest and I intend to carry on doing my job as long as the Prime Minister and the Home Secretary want me to do so," she had said. It is unfortunate for her that, in the case of the Prime Minister, at least, that was to be for around only 24 hours.

The next morning, a Wednesday, Mr Blair's parliamentary secretary was preparing for Prime Minister's Questions when she became aware of the Ainsworth correspondence. Its existence explains Mr Blair's conspicuous failure to defend Ms Hughes or Mr Blunkett as he came under sustained attack on the issue by Michael Howard.

In a tense meeting in his Commons office that afternoon, he heard Mr Blunkett's passionate defence of his minister. The letters should be handed over to Ken Sutton, the man already running an internal inquiry into the Cameron allegations, he said. Mr Blair said he needed more time to reflect. Ms Hughes and Mr Blunkett returned to Mr Blair's office at 7pm. Ms Hughes told the Prime Minister that she did not feel that she could continue.

Mr Blunkett was still determined that she could - and should - remain. "David was railing about the unfairness of it," said one friend.

The meeting that finally sealed her fate was called by Mr Blair in his office when he returned to Downing Street. Sally Morgan, his political secretary, Jonathan Powell, his chief of staff, and David Hill, his press secretary, gathered to read again the letters and the transcripts of her interviews. "The feeling was Bev was right - she probably couldn't survive," said a witness.

By 8.15 the next morning the deed was done and Ms Hughes was led from the Prime Minister's office to that of Mr Hill to begin drafting the personal statement she would deliver in the Commons that afternoon.

There remains genuine sadness this weekend among those close to her and admiration for the way in which she went. "Right to the end she was incredibly self-possessed, cool and collected," said one official who witnessed her final hours as a minister.

Not all Labour MPs were sad to see her go and other ministers said she made an error in seeking to blame civil servants for mistakes on her watch. The whole episode could be swept aside as one of those occasional personal upsets of politics were it not for the subject matter. "The normal thing to say is that it was the cover-up and not the original offence that matters but in this case it was the original offence that really did for her," said David Cameron, the MP for Witney who was Michael Howard's aide when he was Home Secretary, yesterday.

With the Tories and Liberal Democrats stepping up their calls for an independent inquiry, Mr Blunkett faces awkward questions about how much he knew of problems at the front line of immigration control. Although the Prime Minister was quick to deny he was taking "personal charge" of immigration at his monthly press conference on Thursday, the announcement of a Cabinet-level summit on immigration does little for his Home Secretary's credibility.

A Downing Street spokesman said yesterday: "The Prime Minister does not accept that the immigration system is in crisis. He does believe that there has been a decline in confidence in the integrity of some of the processes that has to be addresses and that rooting out abuse is vital to achieving this."

Mr Blunkett's aides insist that he welcomes Mr Blair's intervention. They point out that he has done it before, notably on street crime, when a rise in muggings threatened Labour's reputation on law and order. They also insist the Prime Minster's focus on immigration is not new.

There is a growing feeling that Mr Blair is beginning to lose faith in his Home Secretary. Mr Blunkett has had a few bruising scraps with powerful Blair allies in recent months including a bust-up with Lord Falconer over proposals to weaken the standard of proof to secure terrorist convictions. Although backed by Mr Blair on ID cards, he faces plenty of opponents in the Cabinet, including Jack Straw, the Foreign Secretary.

Now he is on the back foot over the most contentious issue of all, immigration, and the Prime Minister is losing patience. "Blair is terrified that there is something lurking in the system that could really do for us on this - that's why he reacted as he did this week," said a well-placed former minister last week.