Actually, you're both right.
There is nothing to prevent a service policeman from using the general power to arrest anyone (including an officer) who has committed or is suspected of being in the act of committing an arrestable offence, which s.24(4) & (5) Police & Criminal Evidence Act 1984 (PACE) confers on anyone. An arrest for breach of the peace may also be made by any person on anyone.
Outside the UK, however, PACE and 'breach of the peace' powers of arrest do not apply and a service policeman has to rely entirely on his Air Force Act powers of arrest (which currently restrict the arrest of officers).
The advantage of using powers under the AFA (and the new Armed Forces Act, when it becomes law) is that it has the effect of giving the service policeman the very wide powers of arrest over those subject to service law, that a constable has over civilians.
In practice, the change will simply prevent a service policeman having to trawl around for a provost officer, before he can arrest an officer. The new power will be particularly useful where an immediate arrest is necessary, but consulting a provost officer may be impracticable. The increased overseas deployment of the armed forces would appear to make this change necessary.
Last edited by Scud-U-Like; 7th Dec 2005 at 11:14.