Non-Fatal Offences Against the Person Act 1997
Threats to kill or cause serious harm.
5.— (1) A person who, without lawful excuse, makes to another a threat, by any means intending the other to believe it will be carried out, to kill or cause serious harm to that other or a third person shall be guilty of an offence,
(2) A person guilty of an offence under this section shall be liable—
( a) on summary conviction to a fine not exceeding £1,500 or to imprisonment for a term not exceeding 12 months or to both, or
( b) on conviction on indictment to a fine or to imprisonment for a term not exceeding 10 years or to both.