RAF ATCOs
Some country’s military ATCOs are lucky enough to have their military licenses ratified/approved/whatever by ICAO. (e.g. US & Australia). The UK military authorities have constantly refused to do so.
Worldwide ATC employers can use military rated ICAO approved ATCOs in certain places but the disadvantaged Royal Air Force ATCOs are not ICAO recognized and thus have been prevented from applying for these posts due to the fear within RAF ATC command that this would lead to ATCO migration. This is not true of course, as all it does is to prevent RAF ATCOs who leave the RAF at the end of their engagement from using their experience to get further employment. Time for a change ??