A woman has been charged after allegedly threatening people at a hospital with a knife. Police were called to Sittingbourne Memorial Hospital just before 1pm on Monday after reports of a disturbance. Helen Calder, of Tonge Road in the town, was arrested and taken into custody after officers seized a blade from her. The 45-year-old was later charged with threatening a person while possessing an offensive weapon and criminal damage. She was remanded in custody to appear before Medway Magistrates’ Court today. Witnesses said the hospital had gone into lockdown as a result, with one person describ…