Nothing is an offence by reason of any harm which it may cause to a person for whose benefit it is done in good faith, even without that person’s consent, if the circumstances are such that it is impossible for that person to signify consent, or if that person is incapable of giving consent, and has no guardian or other person in lawful charge of him from whom it is possible to obtain consent in time for the thing to be done with benefit:
Provided that this exception shall not extend to––
(a) the intentional causing of death, or the attempting to cause death;
(b) the doing of anything which the person doing it knows to be likely to cause death, for any purpose other than the preventing of death or grievous hurt, or the curing of any grievous disease or infirmity;
(c) the voluntary causing of hurt, or to the attempting to cause hurt, for any purpose other than the preventing of death or hurt;
(d) the abetment of any offence, to the committing of which offence it would not extend.