I note that there have been a number of suggestions that MK are a "flag of convenience" operation. I know that they base some aircraft in the UK and have some offices here. However, I understand that they have more aircraft based in Ghana than the UK and conduct significant operations in that area. If this is the case it would seem quite correct that the airline should have an AOC issued in Ghana. The ICAO requirement is that the AOC is issued by the state in which the airline has its principal place of business.