The row over the Foreign Office’s handling of the Harry Dunn case has deepened over claims a legal loophole allowed Anne Sacoolas to obtain diplomatic immunity.
In 1995, the UK agreed all US staff and their families at RAF Croughton spy base would be protected from prosecution under the Vienna Convention.
Foreign Secretary Dominic Raab has now revealed this was later dropped for workers but records were not changed for spouses so they were still protected.
He described it as an “anomaly” and ordered an urgent review.
The news emerged today, 55 days after Harry’s death, as police announced they will travel to the US to interview Sacoolas, 42, under caution.
Shadow Foreign Secretary Emily Thornberry met the 19-year-old’s parents Charlotte Charles, 42, and Tim Dunn, 50.
She said: “We smell a rat, and we need to find out what really happened. It is dubious and concerning that Mrs Sacoolas was able to claim full diplomatic immunity.
“The FCO and CPS should have challenged the legal basis of her immunity, rather than just blaming it on an anomaly.”
Harry died after he was knocked off his motorbike by Sacoolas near the RAF base in Northamptonshire on August 27.
She told police she was entitled to immunity.
The Foreign Office asked for it to be waived on September 5 but the US refused and she flew home on September 16. Police did not inform Harry’s family until a week later.
Chief Constable Nick Adderley claimed the Foreign Office asked him to delay telling the family while officials worked out the “legal steps”.