A woman from Watford died after the car she was driving left a motorway slip-road and smashed into a tree.

Thames Valley Police is investigating a fatal collision which happened on a slip road where the M25 and M40 meet near Hertfordshire.

Between 10.10am and 10.15am on Friday (July 3), a black Mini was travelling along the exit slip between the M25 anticlockwise and the London-bound M40.

Police say the car left the road, hitting a tree.

The driver, which police say was a woman aged in her 50s from Watford, was pronounced dead at the scene by paramedics.

The woman's next of kin have been informed and are being supported by a family liaison officer.

The slip road was closed for more than four hours as police carried out investigations into the collision, and enquiries are ongoing.

Sergeant Mark Gawthrop, of the joint operations roads policing unit, based at Taplow, Buckinghamshire, said: "We are appealing for witnesses following this incident in which a woman has sadly died.

"Our thoughts are with her family at this difficult time.

"We are carrying out a thorough investigation and we are appealing for anyone who witnessed this collision or anyone who may have dash-cam footage of the incident to please get in touch."

Anyone with information should call 101 quoting reference 43200200317.