A police officer who appeared in the TV show Road Wars has been killed in a motorcycle crash.
Colleagues described him as a "hugely respected officer" and said they were "devastated" at the news.
PC Dixon, 39, died in a collision involving the motorcycle he was riding and a car.
The passenger in the car, a 91-year-old woman, was also killed.
The driver of the vehicle was injured in the incident and has been taken to hospital for treatment. Her injuries are not thought to be life threatening.
Thames Valley Police Chief Constable Francis Habgood said: “My officers, staff and I were devastated to hear the very sad news about our colleague PC James Dixon, aged 39 and the 91-year-old woman who died as a result of a road collision yesterday (5/12).
“James was a hugely respected officer, serving with the force for 18 years in a variety of roles including in Local Policing, Roads Policing and Force Intelligence and Specialist Operations.
“In policing we often talk about the strength and importance of the police family and that is never more so as we share in the pain of loss and offer support to one another at this time of need.
“Our thoughts remain with PC Dixon’s family and friends, as well as those of the 91-year-old woman, at this very difficult time.
"All our force flags will be flying at half-mast for the next week as a mark of respect."
Sky TV's Road Wars followed the work of Thames Valley Police officers.
Fans of the show posted their tributes to PC Dixon on social media.
On Twitter, Ryan Sheehan said: "Growing up I was a big fan of PC James 'Dixie' Dixon and his @tvprp colleagues as they featured in #RoadWars. It's well respected officers like PC Dixon that inspire me to be a Police Officer. My thoughts are with all those who knew him at this very difficult time #PCJamesDixon"
An IPCC investigation to determine the circumstances which led to the collision is underway, confirmed IPCC associate commissioner Guido Liguori.