Gill Walker said the Queen’s daughter-in-law was a passenger in the 4×4 that collided with her vehicle in Birmingham city centre in November last year.
The receptionist claims she was changing lanes at around 6.30pm on November 13 when she was hit by the police vehicle.
She says she stopped and indicated for the driver to pull over to swap insurance details, but instead the police vehicle “just drove off”.
“The police are saying it’s all my fault.”
Ms Walker told Birmingham Live that a second 4×4, which had blue flashing lights, pulled up alongside her Peugeot 107, with officers informing her that a member of the Royal Family was travelling as a passenger in the other vehicle.
She was then allegedly informed that this was the reason the car was not allowed to stop despite the collision.
She also confirmed that officers in the second vehicle exchanged insurance details with her before taking pictures of her car.
She was kept at the scene for two hours after being told traffic officers were being sent to investigate.
The minor crash took place shortly after the Countess opened a military and civilian wound research centre in the city, the first of its kind.
According to Court Circulars, 54-year-old Sophie – wife of the Queen’s youngest son Prince Edward – was the only royal on official duty in Birmingham on the day of the collision.
Four months on from the incident, Ms Walker claims that she is now being blamed for the collision despite having dash cam footage and remains locked in an insurance battle.
She said: “The police are saying it’s all my fault.
“But the dashcam footage shows I’ve clearly got into the lane and they have hit me.
“It’s like they’ve put all the blame on me and they’ve got solicitors involved.
“It looks like it’s going to court because the police don’t want to know.”
A West Midlands Police spokesman confirmed one of its vehicles “was involved in a collision with a third party vehicle during a police operation, resulting in damage to both vehicles as they travelled along a three-lane carriageway.
“Due to operational reasons and force protocol, the vehicle did not stop, but another vehicle in convoy behind the damaged car did stop, and details were exchanged with the third party for insurance purposes.
“A report has been completed by the driver, a police sergeant, and is with the force’s insurers for assessment.”
A Buckingham Palace spokesperson declined to comment on the collision, saying it was “a matter for West Midlands Police”.