(1)A constable may exercise in relation to a person to whom subsection (2) applies any power of the type described in section 47(2) which the constable would be able to exercise by virtue of a rule of law if the person had been charged with the relevant offence by a constable.
(2)This subsection applies to a person who—
(a)is in police custody having been arrested without a warrant, and
(b)has not, since being arrested, been charged with an offence by a constable.
(3)In subsection (1), “the relevant offence” means the offence in connection with which the person is in police custody.