Inspector Bob Jacobs said: "I understand that Sara can be easily confused and her family are understandably concerned that she may come to some harm.
“I believe that it’s likely that Sara is still in the Beaminster area. She is reasonably fit for her age and she has been known to walk considerable distances.”
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People embarking across the Channel should prepare for disruption due to the problems at Calais terminals and the impact of Operation Stack.
The M20 London bound carriageway has now been reopened to traffic but Operation Stack is expected to remain in place into the weekend.
Friday morning's forecast for the east of the region