Inspectors from the Health and Safety Executive (HSE) are at the scene of an incident at the Royal estate at Sandringham.
A spokesman for the HSE said:
No formal investigation has been launched, but we do have inspectors at the scene with police who are making initial enquiries.
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A cloudy and misty start to the day however, during the morning, some brighter spells may develop. Still very mild.
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Low cloud and mist developing overnight. Another mild night ahead. Generally rather cloudy tomorrow, with a few brighter breaks developing.