23. Civil aviation inspectors, as defined in Annex 9 to the Convention on International Civil Aviation signed at Chicago on 7th December 1944(1), where they have travelled to the United Kingdom when engaged on inspection duties.
The latest edition of Annex 9, which is published by the International Civil Aviation Organization, is the 15th edition, which applied from 23rd February 2018 (ISBN 978-92-9258-304-9)