A person who leads, takes or entices away or detains a person with intent to hold that person for ransom or for any other advantage to any person is guilty of an offence punishable, on conviction, by—
(a) if that other person suffers any grievous bodily harm while being so led, taken or enticed away, or detained—imprisonment for 20 years; or
(b) in any other case—imprisonment for 15 years.