A 41-year-old local man, believed to be the driver of the car, was arrested for grievous bodily harm at the time.
This is now being treated as a homicide investigation by Surrey and Sussex Major Crime Team working in conjunction with colleagues in West Sussex Division.
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The Thames Valley Police officer was given a guard of honour by his colleagues at a church in Pangbourne.
The Prime Minister welcomed President Emmanuel Macron to the military academy on the Surrey, Hampshire and Berkshire border.
Thursday evening's forecast for the west of the region