Ms McRae was taken to hospital by helicopter but died later in Nelson Hospital.

A blood sample sent to ESR was found to have a trace of alcohol less than 5mg per 100ml of blood and a cannabis level consistent with having smoked a cannabis cigarette within 30 minutes to six hours prior to death.

It was not possible to determine if she was affected by the drug at the time of her death.

Senior Constable Simon Burbery of the Crash Investigation Unit concluded that while the Toyota was being driven faster than the advisory speed of 75kmh, the speed alone was not enough to cause the complete loss of control.

It was possible Ms McRae was suffering a degree of driver fatigue, having travelled from Westport that morning, which led to her misjudging her speed into the curve, resulting in the need for over correction on exit, Mr Burbery said.

Mr Hart said another motorist stated he had to take evasive action to avoid Ms McRae as she crossed the centre line as she travelled towards the Tapawera township a few minutes before the crash.

The owner of Ms McRae's car informed police he was not aware Ms McRae did not have a driver's licence, but that she was a careful driver and had been using the car for 12 months.

Ms McRae's partner knew she did not have a licence, but said she was a "safety-conscious and competent driver".

Mr Hart said there had been six known serious injury crashes at the site, and cars that left the road at the spot were likely to collide with trees on private land at the roadside.

Mr Smith said he would produce a formal report but was pleased to hear the trees had been removed since the accident.

Mr Smith, who was made Wellington's coroner earlier this year as part of changes to the coronial system, is completing cases in Nelson.