Captain Dart
As an aside some time ago our Flight Safety Department notified me that Australian ATC had 'pinged' one of my flights for having a ONE NAUTICAL MILE track offset without a clearance (our ops manual states 2 nm is OK without informing ATC).
Vol 2/2 doesn't say that at all.
27. STRATEGIC LATERAL OFFSET PROCEDURES
27.1 Strategic Lateral Offset Procedures should only be applied in oceanic airspace by aircraft capable of automatic offset tracking. Certain states may also allow their use in remote continental airspace − if doubt exists, clarification and/or clearance should be sought from ATC. Where part of the airspace in question is within radar coverage, aircraft should normally be allowed to initiate, or continue, the offset.
27.2 Procedure
Offsets of 1 NM or 2 NM to the right of track are authorized.
Crews are not required to inform ATC when applying the offset.
Australia is obviously a state that doesn't allow it's use in remote continental airspace. Therefore you should have obtained a clearance.