23.—(1) Where—
(a)an authorisation under this Schedule authorises the detention of P in circumstances amounting to a deprivation of liberty, and
(b)P is discharged from detention,
the authorisation ceases to authorise any detention of P.
(2) For the purposes of this paragraph P is “discharged from detention” if a person with authority to discharge P from detention informs P in writing that he or she is discharged from detention.