THE Duke of York may have to acknowledge the civil sex case brought against him following reports a judge has ruled the paperwork can be delivered to Andrew’s US lawyer.

Andrew’s legal team have contested whether he has been officially notified about Virginia Giuffre’s claim for damages from the duke after she alleged he sexually assaulted her.

But it has been reported that the judge in the case, US district judge Lewis Kaplan, has ruled Giuffre’s legal team can try delivering the papers to Andrew’s Los Angeles-based lawyer, regardless of whether the duke authorised him to accept it.

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The issue of whether or not Andrew has been notified about the case – known as service of proceedings – was contested during the first pre-trial hearing of the civil case on Monday in New York.

It is an important matter as telling a defendant about legal action being brought against them is the first step in the judicial process.

David Boies, representing Giuffre, said papers had been “delivered to the last-known address of the defendant” and documents had also been sent “by Royal Mail”.

An image of a letter addressed to Andrew – at his Royal Lodge home in Berkshire – being posted in a UK red letterbox has been published online.

Andrew B Brettler, the duke’s attorney, said the royal’s team contested the validity of service to date, adding he has not been properly served under either UK or international law.

In another development, the High Court in London accepted on Wednesday a request by Giuffre’s lawyers to formally contact Andrew about the legal proceedings launched in America.

It is understood Andrew’s team are contesting the court’s decision and the High Court has given the duke’s lawyers seven days to challenge its decision. The High Court said in a statement: “Lawyers for Prince Andrew have indicated that they may seek to challenge the decision of the High Court to recognise the validity of the Hague Convention request for service made by Ms Giuffre’s lawyers.

“The High Court has directed that any challenge must be made by close of business on September 24.”

The news follows revelations that Andrew has not been his usual "blase" self and that the mood on the Queen's Balmoral estate has undergone a "dramatic shift".