The anger of the widow of the murdered Belfast solicitor Pat Finucane remains undimmed two weeks after she ended a meeting with David Cameron in which he declined to hold a public inquiry into her husband's death.

Geraldine Finucane indignantly describes the Government and the Prime Minister as "a disreputable government led by a dishonourable man". Mr Cameron apologised to the Finucane family, saying it was clear that there had been "state collusion" in the murder, but turned down the request for an inquiry. Her continuing campaign has since been supported by all major nationalist parties in both parts of Ireland, the Irish Prime Minister Enda Kenny declaring they "supported Geraldine Finucane in her search for the truth".

The killing of the lawyer was carried out in a murky underworld of agents and informers where many things remain hidden from public view.

A former senior government official privately admits that it was, among Belfast's many security and intelligence controversies, "the smelliest of them all". Three separate intelligence agencies have been shown to have been active around the murder.

The facts of the 1989 assassination of the solicitor are clear enough. He and his wife Geraldine and their three children were having a meal together on a dark February evening when loyalist gunmen arrived.

Mrs Finucane recalls: "We were having our dinner in the kitchen. Basically they just bludgeoned their way through the front door, came up the hall, came into the kitchen and shot Pat."

A detective superintendent called the killing "the most ferocious murder I have come across". He related: "Every shot seemed to strike home. I believe the gunmen involved had murdered before. They were certainly experienced in the use of weapons."

A post-mortem report reveals the lawyer was shot six times in the head, three times in the neck and three times in the torso. It details the clinical nature of the attack, noting: "Any of the wounds to the head, the neck or the torso would have been fatal."

Today Mrs Finucane still lives in the house where her husband died, using the kitchen where she and her children witnessed his death. Did she ever consider moving house? "They've killed my husband but they're not going to wreck the whole bloody family. This is our home and it will remain our home," she says.

The killing had so many suspicious aspects that calls for an official inquiry have been made for many years. When the shooting happened her children were young: now her two sons are lawyers and she has six grandchildren.

Her face lights up when she talks about the grandchildren, whose colourful toys are piled in one corner of her lounge. But it darkens when she recalls the meeting she and her three children had with Mr Cameron.

They were convinced that a public inquiry was on the cards, but instead he informed them a QC would review the papers in the case and report back in December next year. The QC will have no power to compel witnesses to speak to him.

"I cannot remember the last time I felt so angry," she says. "I felt humiliated and insulted - it was a very cruel, devastating experience."

The family had been in contact with the authorities on numerous occasions over the past year, discussing in detail potential models for an inquiry. One, already used in the case of Baha Mousa, a civilian who died in custody in Iraq, was entirely acceptable.

According to Mrs Finucane, the family's hopes were raised when a senior official called to say "The PM wants to speak to the family himself and I think the family will be very pleased with what they'll hear". Instead, he announced the review.

She says: "I asked David Cameron what part the family would play in this review and he said, 'Oh no, no, you don't do anything.' His tone was, 'Don't you worry your pretty little head about it. When the QC finishes he'll tell you what went on.'

"The air was very charged at that point and we put forward the reasons why a review was totally unsatisfactory. Everybody was very angry and obviously devastated but we retained our composure. Voices were raised but nobody was rude. "I thought there was no point in staying there any longer and I said, 'I can't listen to any more of this, I want this meeting to end.' Afterwards, one of the officials said they were quite shocked."

The family had been banking on the promise of an inquiry made by the last Labour government. So why does she think that, 22 years on, none is forthcoming? "Because of what would be disclosed," is her reply. "They really don't want to air the behaviour of the British government and the military, and the policy that was carried on against its own citizens."

Pat Finucane was a prominent Belfast solicitor whose clients included a number of high-profile IRA members such as the hunger striker Bobby Sands. His successes in the courts caused much resentment among the security forces.

According to his widow: "He was too dangerous. It was rocking the boat and the establishment really didn't like that. If you were troublesome they could just take you out - there was no process of catching you and trying you or anything like that.

"If you were troublesome in any way they just got rid of you. They used the loyalist paramilitaries like a regiment in the army to do their dirty work. Then they would back off and distance themselves from it.

"There were a lot of gunmen in Belfast, probably still are, but at that time they were two a penny. It didn't take much to get a gunman to pull the trigger. The question has always been - who put the gunmen up to it?"

But what evidence is there that official agencies were actually involved in murder or at least turned a blind eye to it? Much information is already in the public domain. Sir John Stevens, later Commissioner of the Metropolitan Police, concluded after one of the lengthiest investigations in British police history that there had been collusion.

There was, he said, "Wilful failure to keep records, the withholding of intelligence and evidence, and the extreme of agents being involved in murder so that people have been killed or seriously injured."

Despite solid intelligence that Mr Finucane and others were being targeted, they were not warned, he found. He also said his inquiries were obstructed by the police and army, describing a fire in his incident room as "a deliberate act of arson".

Similar conclusions were reached by a former Canadian judge, Peter Cory, who was tasked by the British and Irish governments with reviewing papers in the case. He recommended a public inquiry after finding strong evidence that collusive acts were committed not just by the police and army but also by MI5.

The judge discovered that MI5 and police had held a meeting to discuss a "very real and imminent" loyalist threat to Mr Finucane's life, but had together decided to take no action. He reported that detectives investigating the killing were not given crucial information, and were not told that one of the murder weapons they were seeking was actually in the keeping of a Special Branch Agent.

While this much is already known, much more embarrassing information would be bound to emerge from a public inquiry. Many observers were therefore puzzled by the fact that the Government gave the impression of seriously considering one.

The crucial question is how far up the chain of command collusion might have gone. Mrs Finucane is definite: "It is to be proven," she says, "but I do think it went to the very top of the security and political establishments. They all worked very much in hand. Everybody was informed as to what was going on."

At this moment the chances of an inquiry seem remote, but Mrs Finucane has support from sources such as human rights groups and, significantly, the Irish government. Dublin has conveyed to London its "dissatisfaction and disappointment" with the announced review.

And Enda Kenny told the Irish parliament of a recent conversation with Mr Cameron: "I indicated quite clearly that, if Geraldine was not happy with what was on offer, then clearly we would not be happy either. I haven't changed my mind."

Geraldine Finucane - I Felt So Angry & Insulted It Was Cruel