Judge Lewis A Kaplan dismissed a motion by the duke’s lawyers to have the civil case thrown out after they argued Ms Giuffre had waived her right to pursue the royal by signing a confidential settlement with disgraced financier Jeffrey Epstein.

The judgment will be a huge blow for Andrew, and media lawyer Mark Stephens said it will prompt meetings of senior royals as they attempt to deal with the looming reputational damage to the monarchy during the Queen’s Platinum Jubilee year.

Mr Stephens told the BBC: “Judge Lewis Kaplan has thrown a reasoned judicial decision like a bomb into the middle and the heart of the royal family and threatens to provoke constitutional crisis as a consequence.”

He said the duke has “no good options”, adding: “Essentially, I think he’s either going to have to engage in the trial process or he’s going to have to settle and that may well be his least worst option.”

Andrew has three main options – ignoring the lawsuit, which is his right, engaging with the American legal system to defend himself against the allegations or attempting to reach an out-of-court settlement with Ms Giuffre.

If he ignores the civil proceedings a default judgement will be made in favour of Ms Giuffre.