A Sheffield student who was accused of carrying a folded knife near Buckingham Palace has had the case against him discontinued.
Hang Zhang, 25, was arrested for possession of an offensive weapon in a public place after being found at the main gate of the royal grounds on August 12.
The Chinese national, of Hawley Street, Sheffield, was subsequently sectioned under the Mental Health Act.
During a hearing at Westminster Magistrates' Court on Thursday, prosecutors confirmed the charges against him had been dropped.
Chief Magistrate Emma Arbuthnot asked if this was due to his 'mental health problems'.
Prosecutor Emily Maunders replied: "Yes, I believe that is the case."
Mr Zhang had previously denied the charges against him during a hearing in October.