The body of Sapper Richard Walker, who died in a shooting in Afghanistan two weeks ago, is being repatriated later. The 23 was originally from Leeds but lived on Wearside.
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The male driver of the motorcycle was pronounced dead at the scene. A driver of another vehicle was taken to hospital.
The warning from NHS England comes two days after Theresa May raised the UK's terror threat level to "critical".
A look ahead at the forecast for the Tyne Tees region.