The Andrew Mountbatten-Windsor Search Warrant - What Went Wrong?

On 8 October 2026 Mr Justice Hilliard quashed a search warrant which had been granted by the Central Criminal Court on the application of Thames Valley Police (“TVP”). The Court has released the High Court’s order and reasons, and it makes interesting reading. 

Gary and James both have extensive experience of applying for, and acting in challenges to, search warrant applications. Here they explain what search warrants are, why rigour is required in applications for them and what happens when matters go wrong. What might have gone wrong for the Thames Valley Police in this case?

What is a search warrant?

Described by Mr Justice Underhill as a “nuclear weapon”[1], a search warrant authorises an investigator to enter premises including an individual’s home. Given a person’s rights in respect of premises, as set out in Art 8 and A1P1 of the ECHR, it is obvious that these are highly intrusive powers. It is a powerful tool that requires a serious approach and rigorous adherence to the legislative requirements.

The judgment referred to different kinds of search warrant and referenced “special procedure” What is that?

Under the Police and Criminal Evidence Act 1984 (“PACE”) there are two available routes to obtaining a search warrant. An application under section 8 can be made to the Magistrates Court. It is primarily used when the Police want to look for a “thing” i.e. a weapon, a phone, or cash on someone’s premises. As part of the test, the judge has to consider is whether there are reasonable ground to believe that the material sought does not consist of “special procedure material”.

PACE defines special procedure material[2] as that acquired or created in the course of a business or trade and which is held subject to express or implied confidentiality i.e. business documentation. 

A section 8 warrant therefore cannot be used if the Police want to search for business documentation. However, there is another route to obtain that kind of documentation: They can seek a warrant pursuant to s.9 of PACE. This application is made before a Crown Court judge.

On an application for a search warrant pursuant to section 9 of PACE part of the test requires that the judge needs to consider is whether he is satisfied that there are reasonable grounds for believing that the material the police want to search for consists of or contains special procedure material.

Therefore law enforcement need to choose the appropriate legislative route, depending on the material they want to search and seize. The crucial task for law enforcement when applying for warrant is to be clear about what they are searching for and why.

What normally happens on an application?

When making an application the Police will complete a specific application form that prompts them to answer, and provide supporting arguments addressing, the specific statutory requirements of the legislation.[3]

On an application for a special procedure warrant the judge has to be satisfied of the following:

• There are reasonable ground to believe an indictable offence has been committed[4]. I.e. an offence that is serious enough to be dealt with by the Crown Court.
• There are reasonable grounds to believe that the material the police want to search for consists of or contains special procedure material on the premises[5].
• There are reasonable grounds to believe that the material sought will be of substantial value to the investigation and that it will be relevant material, i.e. material that could be relied upon in court[6].
• That other methods of obtaining the material have not been successful or that they haven’t tried because they were bound to fail. It is often argued by the Police that they have not tried other methods because if they asked for the documents, the suspect would refused to provide them voluntarily[7].
• That it is in the public interest for the warrant to be granted, given the nature of the proceedings and the general circumstances[8]. 

The judge also has to consider how access could be gained to the material. He needs be satisfied of one of a number of potential scenarios. The most common scenario relied upon by the Police is that if suspect was given notice of the application, it may seriously prejudice the investigation. in other words, if he was notified he might destroy or hide the material before the Police could get access to it[9].  

The application will be accompanied by a draft of the warrant that identified, so far as practicable, the material items that the Police want to search for[10].

Even if all the tests are met the judge has a discretion as to whether to issue the warrant.

The test is therefore extensive and onerous. But by preparing and completing the form, the Police should have ensured that they have addressed the statutory tests and that the judge has all the material needed to decide if a warrant should be granted.

In all but the most straightforward of cases, it would be expected that the Police would engage a barrister to present the case to the judge and for them to have filed a skeleton argument addressing the statutory tests. All these factors should provide an insurance that the judge’s decision will be lawful and not open to challenge.

Is the suspect there at the time of the Application?

Applications for search warrants are made ex parte, i.e. in the absence of the suspect. That is because if you told the suspect about the application is could provide them with the opportunity to dispose of the potentially incriminating material.

However, applications that are made in the absence of a party impose a significant duty of disclosure on the party applying. The Police have to bring all relevant matters to the attention of the court that could affect granting the warrant. They have to put themselves in the shoes of the suspect, telling the judge what the suspect would say if he knew about the application[11]. This is called “The duty of full and frank disclosure”.

In what sort of circumstances can a search warrant or a search be unlawful?

There are a wide variety of ways in which a search warrants can be unlawful:

• If the reasons provided are insufficient for any part of the statutory test to have been met. For example, a frequent challenge to the issuing of a search warrant is whether there were reasonable grounds to believe an indictable offence had been committed.
• If the investigative agent failed to meet their duty of full and frank disclosure based on what the judge was, or was not, told and whether that could have had a material effect on the decision to grant the warrant.
• Specific requirements have not been met[12]. For example, the warrant does not identity with sufficient particularity the items sought or the warrant cannot be understood on its face.
• In relation to the search itself there might be a  challenge if the Police seized something which is outside the scope of the warrant.

What went wrong in this case?

In this case the TVP allowed the judge to grant a search warrant pursuant to s.8 of PACE.

In so doing, the judge would have had to be satisfied that the material the Police wanted to search for did not include confidential business documents. However, given that the Police are investigating Andrew Mountbatten-Windsor in relation to allegations of misconduct in public office, business confidential material was precisely what they were looking for. The High Court order suggests that the Police’s application made clear that they wanted to search for special procedure material.

It also appears that the TVP may have sought section 8 and 9 warrants in the alternative, which may have created uncertainty in their application and confusion in the mind of the judge.

Somehow rather than pressing for a s.9 warrant, which was what was required, the Police allowed the judge to grant them a warrant that did not give them permission to seize the material that they wanted.

As a result when the warrant was executed, the Police unlawfully seized the business documents because they fell outside the scope of the warrant.

Are there any other interesting observations that can be drawn from the High Court’s Order and reasons?

The reasons indicate that after the challenge was made, TVP quicky agreed that the warrant had been issued under the wrong legislation, and they conceded the unlawfulness of the warrant. Because TVP had made that concession, the High Court did not need to consider other challenges that had been made. We don’t know what those other challenges were or whether those grounds would have had any merit. It is possible that those grounds might have involved asking the High Court to consider whether the statutory tests were met, or it could have been argued that TVP failed to tell the judge something that would have been relevant to his decision.

What remains unclear from the High Court Order is how, on such a serious and significant application, the TVP permitted the Crown Court judge to issue a warrant under the Section that did not fit the requirements of the investigation.

What happens next – is the end of the investigation?

All is not lost for the Police. There remains a separate statutory provision pursuant to the Criminal Justice and Poice Act 2001[13] that allows the Police a “second bite at the cherry”. The legislation allows the Police to return to the Crown Court and ask the judge to consider a theoretical application for a warrant. If the tests are met, the Police can ask the Judge to exercise his discretion and let them keep the unlawfully obtained material. In advanced of their application the Police will able to look at the seized material to make their arguments. TVP made such an application on 4 June 2026 under s.59 of the Criminal Justice and Police Act 2001 which is opposed by Andrew Mountbatten-Windsor and will be decided upon next year.

Isn’t that unfair to the suspect

The Courts have emphasised that criminal litigation is not a game[14]. So if the reason for the unlawfulness is a true administrative error, then the Crown Court may well consider that it is in the interests of justice to allow the retention of the material. In exercising its discretion, the Court will however look carefully at the circumstances and in particular whether there has been any bad faith or a fundamental failure to apply the high standards that are expected of applicants[15]. Thus, there have been occasions where the conduct of law enforcement has been so bad that the Court has refused to allow the retention of the material[16].

How can this kind of mistake be avoided?

Careful and detailed preparation is essential. Risks can be mitigated by instructing counsel to advise on the application before it is made, drafting a skeleton to assist the Court and attending the hearing to assist the Judge. Applicants should also ensure that the Judge is not rushed in considering the application and has had sufficient time to read papers in advance.

Gary Pons is a talented and dedicated barrister. Gary is fluent in Spanish. His approach to cases is distinguished by its careful preparation and measured execution. Gary is ranked in both Chambers and Partners (Band 1), and the Legal 500 (Tier 1) for his work in the field of POCA and Asset Forfeiture work. He is recognised in the Lexology Index for Criminal Fraud.

His experience in complex financial crime and asset forfeiture has allowed Gary to develop his practice over the years. Gary has experience of foreign criminal proceedings having been involved for many years with two high-profile cases in Costa Rica. He frequently advises on multi-jurisdictional asset recovery cases.

James Fletcher practises in both civil and criminal law. He is a specialist in Asset Recovery, money laundering and Proceeds of Crime work. He has significant expertise in dealing with Account Freezing, Listed Assets and Forfeiture applications in the Magistrates' Court and Civil Recovery in the High Court. He is instructed on behalf of businesses, by individual members of the public and by Government departments.James has extensive expertise in applications and judicial reviews relating to law enforcement investigations such as search warrants, restraint, disclosure orders, receiverships, and moratorium extensions. 

He has been featured in Chambers and Partners in the field of Proceeds of Crime and Asset Forfeiture work (all circuits) since 2014 and has been “Top Ranked” since 2016. James is ranked as a Tier 1 leading individual in The Legal 500 for POCA and Asset Forfeiture (London Bar).