Brendan
I dont need to look thank you, since I never referred to the FIRs, just pointed out that I thought you were wrong in your original assertion. I already knew what territorial airspace meant.
Mind you, things are rarely as simple as they seem when it comes to anything aviation related. You might like to consider:
A flight from an OT to an off-shore oil rig is not an international flight if the rig is within the territorial waters of the OT concerned. Normally territorial waters would extend to 12 miles from the shoreline but can extend further under international treaty or by a claim of sovereignty. Normally, therefore, operations between an OT and an oil rig in international waters that do not pass through the airspace of another country will not be international.
If the rig were located in the undisputed territorial waters of another Contracting State then the flight would become an international one.
My bold.