Obbie ...
The relevant section from the previous Tax Convention signed in 1979 read:
3. Notwithstanding the preceding provisions of this Article, remuneration in respect of an employment exercised aboard a ship or aircraft operated in international traffic by an enterprise of a Contracting State, shall be taxable only in that State.
The 13 words "
unless the remuneration is derived by a resident of the other Contracting State" that they added in to the new convention make all the difference.