Complex sentence: Authorisation to remove Carbine's required authorisation on the control room once they had contacted an officer of ACPO rank, if a high ranking officer could not be sought to gain authorisation, in an emergency it could be given by a Chief Inspector.
Split into simpler sentences: Authorisation to remove carbines required authorisation from the control room once they had contacted an officer of ACPO rank. If a high ranking officer could not be sought to gain authorisation, in an emergency it could be given by a Chief Inspector.