Foreign Secretary Dominic Raab is set to hold a “vitally important meeting” with the family of teenage motorcyclist Harry Dunn ahead the US Secretary of State’s visit to the UK.

Mr Dunn’s parents have said they are confident talks with Mr Raab will be “constructive and productive” – adding that it is “more important now than ever” to be on the same page.

The 19-year-old’s mother, Charlotte Charles, and father, Tim Dunn, have disputed the Foreign Office’s claim that the suspect had diplomatic immunity at the time of a road crash which killed their son.

Harry Dunn death
The family of Harry Dunn (left to right) mother Charlotte Charles, stepfather Bruce Charles, family spokesman Radd Seiger, father Tim Dunn and stepmother Tracey Dunn (David Mirzoeff/PA)

Mr Dunn was killed when his motorbike crashed into a car outside a US Military base in Northamptonshire on August 27 last year.

Anne Sacoolas, the wife of a US intelligence official based at RAF Croughton, was granted diplomatic immunity after the crash and was able to return to her home country, sparking an international controversy.

The Home Office submitted an extradition request for the 42-year-old which was rejected by Mike Pompeo on Thursday.

A spokesman for the US State department said if the extradition request was granted, it would render the invocation of diplomatic immunity a practical nullity and would set an extraordinarily troubling precedent.

Mr Dunn’s parents have said they expect the Foreign Secretary to make it clear there will be “severe consequences” if the US government continues to refuse to return Mrs Sacoolas after their meeting on Monday.

Mr Pompeo is set to have a meeting with Mr Raab on Wednesday.

On Sunday, Brexit Secretary Steve Barclay continued to assert the government’s position that they would not give up on getting Mrs Sacoolas extradited.

“We continue to work on that because we feel it is denying the family justice for her not to return to answer the questions that they have,” he told the BBC.

The Prime Minister “reiterated the need” for Mrs Sacoolas to return to the UK during a phone call with Donald Trump on Friday.

UN General Assembly
The two leaders discussed the case on Friday (Stefan Rousseau/PA)

“The Prime Minister raised the tragic case of Harry Dunn and the need to secure justice for Harry’s family,” a Downing Street spokeswoman said.

Speaking ahead of the meeting with the Foreign Secretary, the spokesman for the Dunn family, Radd Seiger, told the PA news agency: “Harry’s parents are very much looking forward to meeting with Dominic Raab tomorrow.

“This is a vitally important meeting for the government and ourselves. We have not always been on the same page but it is more important now than ever that we are.

“Pompeo relies on the assertion that Anne Sacoolas had diplomatic immunity at the time of the crash with Harry. To this point, the UK Government backs that claim, although argues that it lapsed when she returned to the US rendering her capable of prosecution.

“On legal advice, the family’s position is that she nor anyone else at RAF Croughton never had immunity in the first place.”

Mr Seiger continued: “Pompeo says he is coming to reaffirm the special relationship. That is all well and good, but we expect the FCO to make it clear to Pompeo that his unlawful harbouring of Anne Sacoolas will not be accepted, to demand her return as they have done so already and to make it clear that there will be severe consequences if the US Government will not return her.

“The family are confident that these talks with the Foreign Secretary will be constructive and productive. We all want the same thing which is to ensure that the rule of law is upheld.

“No one is above the law. Not even so-called diplomats from Croughton.”