On 18 February, Thames Valley Police asked for permission from the Central Criminal Court for warrants to search Wood Farm in Sandringham and Royal Lodge in Windsor.
The request included the police outlining the scenarios in which they believed they would need search warrants to ensure access to the properties.
They feared that Mountbatten-Windsor or his legal team would want to see “judicial authority” before allowing the police to enter, the documents show.
The police were concerned that Mountbatten-Windsor or his representatives could argue that the Sandringham Estate was the property of King Charles – and that it would be a slow process getting a separate right of access.
Such a delay would “frustrate the nature and purpose of the search,” said the police, in their application for search warrants.
There was also a concern that no one would be present at the property and that media attention could be drawn to the police presence outside while not being able to enter.
Any of those delays could have meant the police would have been unable to gather the evidence they wanted, they argued – and “given the gravity of this investigation”, the police asked for search warrants.
In separate documents filed as part of Mountbatten-Windsor’s legal challenge against the warrants, his lawyers said: “These assertions were no more than speculation.”
The documents also detail the type of information the police were seeking inside the properties.
They say: “Paper-work, diaries, business records or other documentary evidence of AMW’s [Andrew Mountbatten-Windsor’s] time as Special Representative for Trade and Investment.
“Further evidence as to any action, communication, comment or in relation to matters following the release of material by the FBI concerning the late Jeffrey Epstein as AMW will be aware that Thames Valley Police is conducting an assessment.
“Specifically mobile phone(s) and computer(s) [to include electronic notebooks, surfaces, iPads and any older electronic devices,” which could have held information about links to Epstein at the time when Mountbatten-Windsor had been the UK’s trade envoy.”
The documents show the search of Royal Lodge, Mountbatten-Windsor’s former home in Windsor, continued until 24 February.
They also reveal his police interview at Aylesham Police Station began at 15:00 GMT and he was released under investigation at 18:36.
The legal documents give details of why the police wanted to talk to Mountbatten-Windsor, including the claim that when he was a UK trade envoy he had forwarded Jeffrey Epstein official reports from official visits to Singapore, Vietnam, China and Hong Kong.
There was also a claim, arising from emails in the Epstein files released in the US, that Mountbatten-Windsor had briefed Epstein on investment opportunities in Afghanistan.
Also mentioned is the suggestion Mountbatten-Windsor held meetings with a private investment firm and then suggesting to Epstein that he might invest in the company.