FJJP...
The Snowdrops can and always have been able to arrest anyone, regardless of rank, who was committing an arrestable offence or where an arrestable offence had been committed if they suspected the said officer, SNCO, airman and civilians of committing the offence they could arrest that person without a warrant. Basic common law. Statute law, common law and case law forms the main part of military law from which the snowdrops obtain their powers from. Air Force Act '55 etc.
Local procedure might have been that the chief Snowie wanted to be informed before such an event but this is not infact needed to give the LAC/A/CPL Plod and ranks above, the power to arrest Air Com Thug, F/L Bruiser or W/O Thrasher from beating his wife up, deliberately damaging his neighbours car, or nicking the silver from the Mess etc. etc.etc. (and a whole host of other arrestable offences too) The powers are rank free.