Barnes, from Baydon near Swindon, was also driving erratically when she hit and killed teacher Diane Wright in September 2010. Her car was crushed and she died at the scene.
Barnes is at Swindon Crown Court for her sentencing, having eventually pleaded guilty to dangerous driving after going on the run in Holland for 18 months.
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Jeremy Corbyn's visit has been one of the big talking points of another busy day at Glastonbury.
The Labour leader said socialist politics would not be put "back in a box" as he appeared on stage at the festival.
Turning windier with a few showers