Sir David Calvert-Smith: The butler, his evidence and a delicate issue of calling the Queen as a criminal case witness

The Monday Interview: Director of Public Prosecutions

The ferocity of the public outcry that followed the collapse of the trial of the former royal butler Paul Burrell last year still haunts Sir David Calvert-Smith.

The Director of Public Prosecutions believes the Crown Prosecution Service was made a scapegoat for unique events beyond the control of any prosecutor or policeman. After all, he asks, how many other cases have collapsed because of the intervention of the monarch?

"There has been a great deal of criticism ... that it took until the middle of the trial for this information to be known ... that Her Majesty had had a conversation with Burrell," says Sir David, who leaves today after five years in charge of prosecutions in England and Wales.

He says that the Metropolitan police who interviewed Mr Burrell would have had to have been clairvoyants to establish the truth. "They did ask him about the very conversation in which it now turns out he had said something about taking the late Princess Diana's property for some kind of safe-keeping, but he steadfastly did not reveal it."

When Mr Burrell's defence statement was sent to the CPS there was still no hint of the momentous events his trial was about to trigger.

"There was no reference to his having told Her Majesty about this, or that he thought he had some kind of implied authority from the head of state to look after this property," Sir David says. "Most defendants tell you what their defence is if they don't want to be charged or want to be acquitted."

The truth is, Mr Burrell had not even confided in his own lawyers. By the time he decided to make his disclosure, the trial had reached a critical point. At CPS headquarters in Ludgate Hill the revelation was met with astonishment. As lawyers began working through the implications there was a real possibility that the defence might want to call the Queen as a witness.

Sir David acknowledges for the first time since the collapse of the case that the CPS was forced to prepare for this, and instructed a senior barrister, an expert in constitutional law, to establish whether the Queen could be called as a witness in her own court.

"I am reasonably clear Her Majesty would be competent to give evidence should she wish to do so. The question is, if she didn't wish to do so, could she be compelled to do so? That's an issue to which I can't give an authoritative answer."

Sir David says that would have to be decided by a court ruling, perhaps the law lords. He says the head of state could be assaulted when they are the only witness. "Then he or she, whoever it happens to be, would have to make up their minds whether they wanted to go to court."

But why did the Burrell evidence take two days to become public knowledge? To conspiracy theorists, this fuelled suspicion of a constitutional and royal cover-up.

"It seemed to counsel then, and I believe he was absolutely right, that it was necessary to explain to the judge, initially behind the scenes, what might be happening. They wanted to know exactly what Her Majesty was saying because it was fourth or fifth-hand when we first heard it. Check out exactly what it was, then have a careful look at the case and then decide whether the case should proceed. I think that was the only way it could have been handled properly."

Sir David wants to put the record straight on another case where he believes the CPS has been unjustifiably criticised. "Fiasco, débâcle and shambles" were typical of the headlines that followed the acquittals of the four youths accused of murdering Peckham schoolboy Damilola Taylor.

"No doubt there was a considerable public desire, as there was within the CPS, that those who were responsible for the killing of Damilola Taylor should be brought to justice," he says. "And there is an understandable feeling of disappointment, not just in the minds of the family but in the public.

"Every effort made by the defence before and during the trial to bring the trial to a halt because of alleged deficiencies in the evidence was rejected. The case was left to a jury to try. The jury did spend three days discussing their verdicts and they eventually acquitted. That is the criminal justice system at work. The prosecution should not only bring cases in which a conviction is certain or virtually certain, it should bring cases that are put before a jury, who are the proper people to make the decision, not the prosecutor."

Reviews of the case showed the prosecution team could have done more between the time of the arrest and trial. Since these reports were published, Sir David and Sir John Stevens, the Metropolitan Police Commissioner, have been looking at ways to forge a closer working relationship.

But, in the Burrell and Damilola Taylor cases, the public perception persists that the CPS lost. "Because we were for the prosecution we caught the flak," Sir David says. "But I don't believe it was deserved.We review every case where we get a bad result to see what lessons can be learnt. The great progress is that we are now reviewing with the police in a more systematic way because the faults tend to straddle both sides." He says with the evidence, "we would have caught far worse flak if we didn't prosecute".

Sir David's five-year record as DPP will also be judged on his handling of internal challenges. Perhaps the most testing has been the investigations into racism. He has been forced to concede the CPS is guilty of institutional racism. This led him to commission an independent review of 13,000 cases to establish whether institutional racism had infected the decision-making. The findings last month concluded no such link could be established.

Although it was not possible to prove individual prosecutors were guilty of direct or indirect bias, statistics showed Afro-Caribbeans and Asians were "brought to trial on a less sound basis than white defendants". The CPS was more likely to object to bail for black defendants and more likely to claim they would "obstruct justice" than for defendants from other ethnic groups.

These are now issues for Sir David's successor, Ken Macdonald QC, an eminent human rights barrister who has already been given a harsh lesson on what to expect from the media.

After his appointment was announced, reports circulated about a cannabis conviction 30 years before, in his student days. Questions were asked about his ability to prosecute drugs cases effectively. Sir David says something "that old and that trivial" should not have weighed in the balance. "Most of the senior police officers I have spoken to say it's good to have someone who has lived a bit."

The CV

Born: 1945

Education: Eton College and King's College, Cambridge

Status: Lives in London and is married with two adult children

1969: Called to the Bar

1986: Junior Treasury Counsel

1991: Senior Treasury Counsel

1995-97: First Senior Treasury Counsel

1997: QC

1997: Chairman of the Education and Training Committee of the Bar Council

1998: Chairman of the Criminal Bar Association

1998 to date: Director of Public Prosecutions