APPEAL COURT, HIGH COURT OF JUSTICIARY
 HCJAC 26
Lord Drummond Young
Sheriff Principal Pyle
OPINION OF THE COURT
delivered by LORD BRODIE
THE APPEAL UNDER SECTION 174 OF
THE CRIMINAL PROCEDURE (SCOTLAND) ACT 1995
PROCURATOR FISCAL, GLASGOW
Appellant: Collins, Solicitor Advocate; Capital Defence Lawyers
Respondent: Brown, QC; Crown Agent
11 February 2015
 The appellant has been charged on summary complaint at the instance of the respondent in the Justice of the Peace Court of the City of Glasgow with, on 15 August 2013 at Bellahouston Park, Glasgow, having in her possession a small quantity of cocaine in contravention of section 5(2) of the Misuse of Drugs Act 1971. On 25 April 2014, in answer to the complaint, the appellant pled not guilty. The court adjourned the case for trial on 21 October 2014 with 23 September fixed as an intermediate diet. At a continued intermediate diet on 15 October 2014 the appellant’s agent sought and was granted leave of the court to intimate late a plea in bar of trial based upon oppression. On 12 November 2014 the appellant’s agent intimated and lodged a compatibility minute stating the appellant’s intention to raise a compatibility issue within the meaning of section 288ZA(2) Criminal Procedure (Scotland) Act 1995. As the stipendiary magistrate observes in her report to this court, the point set out in the compatibility minute is in the same terms as the oppression point. After hearing parties at a diet of debate on 12 and 19 November 2014, the stipendiary magistrate repelled the plea in bar of trial and continued the compatibility minute to the trial diet. The stipendiary magistrate granted leave to appeal her decision repelling the plea in bar of trial, in terms of section 174(1) of the 1995 Act.
 The appellant is represented by Mr Simon Collins, Solicitor Advocate. Mr Collins appeared before this court to move the appeal from the decision of the stipendiary magistrate. It was Mr Collins who had argued the plea in bar at trial before the stipendiary magistrate. Mr Collins was also party to a telephone call with a depute of the respondent during which Mr Collins disclosed information which, he submitted to us, was thereafter used by the depute in a way which was improper and so unfairly prejudicial to the appellant that it would be oppressive to allow the matter to proceed to trial.
Factual circumstances relied on by the appellant
 The circumstances founded on by Mr Collins in support of the plea in bar of trial before the stipendiary magistrate and in the appeal before us are as follows. The allegation which provides the substance of the charge against the appellant, as it appears from the summary of evidence disclosed by the respondent, is that on 15 August 2013 police officers, including Police Sergeant Blair Pettigrew, were on foot patrol within the area of a music concert in Bellahouston Park, Glasgow. Their attention was drawn to the appellant who was in the company of another woman. The officers suspected that the appellant was in possession of a controlled drug in contravention of the 1971 Act. Accordingly, they searched the person of the appellant in purported exercise of the power conferred on them by section 23(2) of the 1971 Act. They found a wrap of white powder weighing some 2.5 grams. It is alleged that the white powder was cocaine. The circumstances specified in the summary of evidence as giving rise to the police officers’ suspicion were that the appellant’s eyes appeared glazed over and her speech was slightly slurred. The white powder is stated to have been found in the appellant’s handbag.
 Subsequent to the service of the complaint upon the appellant, on 20 January 2014, there was a telephone conversation between, on the one hand, Mr Collins and, on the other, Mr Barry Dickson, one of the respondent’s deputes. The content of that telephone call is summarised in paragraph 3(b) of the compatibility minute as follows:
“The [appellant] instructed her solicitor to contact the Procurator Fiscal with a view to discussing the case and attempting to persuade the Procurator Fiscal to discontinue proceedings against her. The [appellant’s] solicitor thereafter contacted the Procurator Fiscal’s office in Glasgow by telephone, on 20 January 2014, and spoke with Mr Barry Dickson, Procurator Fiscal Depute, at that office. In his discussion with Mr Dickson the [appellant’s] solicitor advised Mr Dickson that the [appellant’s] position was that the drugs belonged to the [appellant’s] sister, who was with her at the time of the search, and who explained to the searching police officers that the drugs were contained within a makeup bag that the [appellant] was carrying for her. The [appellant’s] solicitor further discussed the terms of the summary of evidence in relation to the reasons given for the purported section 23 detention and search of the [appellant]. The [appellant’s] solicitor expressed a view to Mr Dickson that the search would not be lawful on the basis set out in the summary of evidence ... In particular the [appellant’s] solicitor explained to Mr Dickson his contention that the search was based solely upon the [appellant] appearing to be under the influence of something, whilst in licensed premises. There was nothing to suggest that she was under the influence of drugs specifically, and as such there was no basis for a reasonable suspicion that she was under the influence of drugs. Following upon the discussion, Mr Dickson indicated that he was not prepared to discontinue proceedings and the [appellant’s] solicitor confirmed a plea of not guilty would be tendered.”
 On 11 September 2014 the respondent disclosed to Mr Collins, as the appellant’s solicitor, a copy witness statement prepared by Sergeant Pettigrew and setting out his evidence. The witness statement included the following paragraphs:
“I was on duty on 15 August 2013 and my duties included a proactive plain clothed patrol within Bellahouston Park where the group “Kings of Leon” were performing. I was accompanied by police witness McFadden and Porter.
About 1640 hours I, observed the now accused enter a toilet cubicle with another female, these portable toilets are very small and I immediately formed the opinion that the accused was entering to use controlled drugs.
After a few minutes I observed the accused exit the cubicle, she was unsteady on her feet and I walked towards her I noticed her eyes to be glazed, this confirmed my suspicions that she had been using controlled drugs.
I have since been made aware that the accused has claimed she informed me at the time that she was holding the wrap of powder for someone else, I can confirm that this is not the case at no time did the accused make these claims.”
The consequential unfairness complained of by the appellant
 The substance of the appellant’s complaint that it would be unfair and therefore oppressive if the respondent were permitted to proceed to trial is set out in the following passages in paragraph 3 (d) and (g) of the compatibility minute:
“(d) …It is the [appellant’s] belief that the Procurator Fiscal Depute, as well as advising the reporting officer about the [appellant’s] defence to the charge, also advised the reporting officer of the deficiency of the detention…
(g) …as a result of the actions of the Procurator Fiscal’s Office in Glasgow, and Mr Dickson specifically, the [appellant] has been deprived of her right to a fair trial as guaranteed by article 6 (1) of the European Convention on Human Rights. The police witnesses, who are the only witnesses against the [appellant], have been advised and forewarned of the defence to be relied on by the [appellant]. The witnesses have been advised of her position at a time before they have even provided statements setting out the basis of the prosecution. Given the change in justification for the search from the summary of evidence to the statements it is the [appellant’s] position that the witnesses against her have altered their position to meet the challenges she would have raised in her defence. She has accordingly been prejudiced and has been deprived of her right to a fair trial.”
These averments were slightly elaborated upon by Mr Collins in submission. He pointed to Sergeant Pettigrew’s statement as indicating that the officer had been made aware of what had been communicated by Mr Collins to Mr Dickson during the telephone conversation on 20 January 2014. This, Mr Collins said, was unfair. Mr Dickson had forewarned Sergeant Pettigrew of what would be put to him in cross-examination. In particular he had forewarned Sergeant Pettigrew of Mr Collins’s contention that if, as appeared to be the case on consideration of the summary of evidence, the police officer had formed his suspicion of the appellant being in possession of controlled drugs on the basis of her eyes appearing glazed over and to her speech being slightly slurred, these were not reasonable grounds, given that Sergeant Pettigrew had encountered the appellant in what were licensed premises where she might be expected to have consumed alcohol. What Mr Dickson had done was wrong. As he had decided not to discontinue proceedings, there had been no need to contact Sergeant Pettigrew at all. What had been said to him by Mr Collins during the telephone call on 20 January 2014 had been confidential information. Mr Dickson was not free to pass it on. By doing so he had placed Sergeant Pettigrew in an equivalent position to the witness who has heard previous evidence in the case before he is called on to give his testimony.
 The stipendiary magistrate had repelled the plea because, at that stage in the proceedings, she could not conclude that a fair trial was impossible for the appellant. Essentially, she had taken the view that the objection raised on behalf of the appellant was premature. Mr Collins argued that the stipendiary magistrate had been wrong to take this view. Where prejudice can be demonstrated, it is not premature to uphold a plea of oppression: Mowbray v Crowe 1993 JC 212, HM Advocate v Fleming 2005 JC 291. In any event the appellant’s position was stronger before this court than it had been before the stipendiary magistrate. The stipendiary magistrate had understood that for the purposes of trial the appellant’s agents would be provided with copies of the correspondence between the procurator fiscal’s department and the police and that they would have access to the relevant police notebooks. The position now taken by the Crown was to decline to produce police notebooks or the original report from the police upon which the summary of evidence had been based. There was a requirement for transparency. That was absent in the present case. Justice had to be seen to be done.
The respondent’s position
 The advocate depute submitted that nothing untoward had happened in this case. On his information Mr Dickson had advised Mr Collins on 20 January 2014 that he would not be discontinuing proceedings on the basis of the existing evidence. The telephone conversation had also included Mr Collins making representations about the risk to the appellant’s employment in the event that the prosecution went ahead. What Mr Dickson had then done was what any responsible procurator fiscal depute would have done: ascertain whether there was an evidential basis for what was put forward as a reason for discontinuing proceedings. It was not accepted that Mr Dickson had discussed Mr Collins’s criticism of the reasonableness of police suspicions with Sergeant Pettigrew. There was no question of the conversation between Mr Collins and Mr Dickson being regarded as confidential in nature. A summary of evidence such as was provided here is simply copied from the Standard Police Report. As a matter of routine, police officers are requested to prepare witness statements in summary matters only when a plea of guilty has been tendered. All matters relating to fairness could be dealt with at trial. The appeal should be refused.
 As we understood Mr Collins’s submissions, his complaint that continuation of the prosecution amounted to oppression had two aspects, upon both of which he relied. First, the appellant had been put at a forensic disadvantage as a result of Mr Dickson having passed on to at least one of the police witnesses information as to the appellant’s version of the critical events; Mr Collins’s cross-examination would no longer have the element of surprise. Second, Mr Dickson’s actions had been improper; he had breached the confidentiality which had attached to his conversation with the appellant’s solicitor. Although he did not expressly articulate it this way during oral submissions, looking at the averments in the compatibility minute which are quoted above, the thrust of Mr Collins’s complaint seemed to be that if not the purpose of Mr Dickson’s communication with Sergeant Pettigrew, then its effect had been to tutor a material Crown witness and therefore irrevocably taint his evidence. To proceed with a trial would therefore be unfair.
 We do not propose to offer a comprehensive definition of what amounts to oppression for the purpose of a plea in bar of trial but we would accept that when circumstances have arisen such as to make a fair trial impossible that would justify upholding the plea. That the court disapproves of the conduct of the prosecutor in the matter will not be determinative but it may be relevant. Where the prosecutorial misconduct results in giving the Crown a clear forensic advantage, or puts the defence at a clear disadvantage, as in the case of Mowbray v Crowe supra, then that will provide a strong indication of oppression and the plea is likely to be upheld. Mr Collins sought to equate the circumstances of the present case with those in Mowbray. In our opinion that cannot be done. In Mowbray a young woman of 17 had been cautioned and charged by the police with an assault on a child. The procurator fiscal invited her to an interview in order to discuss her case with a view to determining whether it was suitable for diversion from prosecution by the giving of a warning. She was not warned that she need not attend for interview or advised that she might wish to take legal advice and, should she chose to attend, be accompanied by a solicitor during any interview. The young woman attended an interview with a procurator fiscal depute, accompanied by her mother. Following the interview she was prosecuted. That was the context in which the Lord Justice Clerk (Ross) delivering the opinion of the court said this (at p218)
“The appellant was an individual who had been cautioned and charged and accordingly she could not have been questioned by the police. In our opinion it was equally wrong that she should be questioned by the procurator fiscal at an interview. Following upon this interview, the procurator fiscal served the complaint upon the appellant and, accordingly, having had this interview with the appellant, the respondent was prosecuting her after he had interviewed her and ascertained what her defence was. That appears to us to be an improper way for a prosecutor to proceed.
… knowing what her defence is must give the Crown an advantage which it would not have had if the interview had not taken place. Not only that, but it is well established that justice must not only be done but must be seen to be done and in our judgment justice is not seen to be done if the prosecutor has behaved in the way in which the respondent behaved in the present case, by interviewing the appellant without warning her that she did not require to attend for interview nor advising her that she might wish to take legal advice and could be accompanied by a solicitor at the interview. By doing so, he secured for the Crown an unfair advantage in any subsequent trial of the appellant on this complaint.
In all the circumstances, we are satisfied that there was oppression in the present case and that the justice ought to have upheld the plea in bar of trial.”
 In the present case parties are not entirely at one on the facts. We did not understand Mr Collins to accept the accuracy of the information provided by the advocate depute that Mr Dickson’s recollection of the conversation is to the effect that he specifically told Mr Collins that he would contact the reporting officer about what Mr Collins had told him that Mr Collins had been told by the appellant. Equally, while Mr Collins draws the inference that the police were told of Mr Collins’s proposed challenge to the legality of the detention and search, according to the advocate depute whereas the reporting officer was advised that it was claimed by the appellant that the bag she was holding (containing the drugs) belonged to her sister, that her sister was present and had confirmed this, nothing was communicated about Mr Collins’s criticisms of the reasonableness of the grounds for suspecting that the appellant was in possession of controlled drugs which appear in the summary of evidence. However, even if it be assumed for present purposes that Mr Dickson said nothing to Mr Collins about referring what he had been told to the reporting officer and that Mr Dickson did then alert Sergeant Pettigrew to the proposal to challenge the reasonableness of the police suspicions, we do not accept that there has been anything improper about the conduct of the respondent or any of his deputes in this matter. This makes the case clearly distinguishable from Mowbray v Crowe. Here the appellant’s solicitor disclosed what he chose to disclose to the respondent’s depute with the perfectly legitimate purpose of persuading the depute to make a decision favourable to the appellant. Now that may have had the result that the Crown thereby ascertained what the appellant’s defence was, as occurred in Mowbray, but the means were different. There was no question of Mr Collins having been tricked or misled or taken advantage of. Mr Collins did submit that, although nothing was explicitly said on the matter, he was entitled to regard the conversation with Mr Dickson to have been confidential in the sense that Mr Dickson was under an obligation not to divulge its contents to any other person, and certainly not the reporting officer. We found that submission extraordinary. We entirely accept that circumstances may be such as to make a telephone call between the representatives of parties to a proposed prosecution confidential. This does not apply here. We can see no purpose in Mr Collins saying what he did about the strengths of his client’s case other than to point Mr Dickson’s inquiries in certain directions with a view to confirming what Mr Collins had said and, having done so, discontinuing the prosecution. The logic of Mr Collins’s position was that Mr Dickson was bound either to accept or reject the accuracy of what the appellant had told Mr Collins without any further inquiry. If that is what Mr Collins thought when he was making the telephone call, he was not entitled to do so. We would see Mr Dickson to have been in dereliction of duty had he not made inquiry of the reporting officer as to the accuracy or otherwise of what Mr Collins had represented to him as the true sequence of events. On Mr Collins’s version of the telephone call, Mr Dickson gave him to understand at its close that he had made a final decision not to discontinue the prosecution. We would not understand that to be Mr Dickson’s position, but, again, even if Mr Collins is taken as correct and Mr Dickson said he had made his decision, we do not see him as thereby prevented from revisiting the question as to whether this was a prosecution which it was in the public interest to continue and, with a view to further informing himself, making inquiry of the reporting officer.
 Mr Collins accepted, as a matter of generality, that it was entirely proper that Crown witnesses be precognosced. While we do not suggest that what occurred here was a full precognition of Sergeant Pettigrew, putting to a witness a particular version of events for the witness’s comment is a usual part of the precognition process and therefore Mr Dickson cannot be faulted in that respect. There has been no attempt on the part of the Crown or the police to conceal that Sergeant Pettigrew has been advised of the appellant’s version of events. That is stated in terms in his disclosed witness statement. Mr Collins argued that given that Mr Dickson had determined by the end of the telephone call that he would not discontinue the prosecution, there was no need for him further to communicate with any police officer. That, in our opinion, was entirely a matter for Mr Dickson, even if that had indeed been his decision. Mr Collins said it is wrong to “coach” a witness and no doubt that is so but that is not what is said was done here. What is said, albeit as a matter of inference, is that police witnesses “have altered their position”. In other words, these witnesses will be other than entirely candid when they come to give evidence at trial. Whether or not this turns out to be so is a question for future resolution. Any available point, as the stipendiary magistrate correctly observed, can be taken by the appellant at trial when the credibility and reliability of all the witnesses who are led can be fully tested.
 As it appears to us, this matter was dealt with entirely appropriately by the stipendiary magistrate. In particular she recognised the question of fairness or oppression, whether under the common law or in relation to the compatibility of the proceedings with article 6 of the European Convention on Human Rights, can normally only be determined at the conclusion of proceedings, except in what have been described as exceptional and blatant cases: Fraser v Deveney 2014 SCCR 147. She made her decision accordingly. She has not been shown to have erred in any respect. We shall accordingly refuse the appeal.