Prosecutor Michael Mather-Lees said her Subaru veered to the right to avoid a collision but clipped the Rover in doing so, colliding with the Fermors' Saab, which was also travelling in the opposite direction on the national speed limit road.

The prosecution said the manner of Ms Mead's driving "fell far below the standard of a competent motorist".

I have ruled as a matter of law that the prosecution are not in a position to prove causation in relation to the offence of death by dangerous driving

Judge Helen Mifflin

But Judge Helen Mifflin ordered the jury forewoman to return not guilty verdicts in respect of two counts of causing death by dangerous driving after ruling there was insufficient evidence to secure a conviction.

She said the prosecution's decision not to call the driver of the Rover, who was also involved in the incident, would lead the jury to speculate about that part of the accident.

"I have heard legal argument whether the offences the defendant faces on the indictment can be properly made out," the judge told the jury.

"I have ruled as a matter of law that the prosecution are not in a position to prove causation in relation to the offence of death by dangerous driving.

"I have ruled that, in order for you to deal with that, you will have to deal with the incident between the third driver and the defendant's Subaru.

Condolences to family

"In the absence of evidence from any witnesses in respect of that incident, and in the absence of any evidence from the third driver herself, that is asking you to reach a verdict on these counts which will involve you speculating."

Judge Mifflin said the court offered its condolences to the family of Mr and Mrs Fermor.

A visibly relieved Ms Mead was then formally discharged from the dock and was able to join her family in the public gallery.

After a short adjournment, Mr Mather-Lees told the court that a charge of dangerous driving would not be pursued against Ms Mead.

After the case, the family of Ms Mead said she had no comment.