I discovered today a new/updated flag of the IMSO (International Mobile Satellite Organization) The flag in the photo behind the new director general shows a white flag with dark blue letters "IMSO" and Below them the stylized knot un UN blue box with the full name of IMSO below it in smaller letters.
The flag (as shown as a logo of the current private co Inmarsat . It is similar to Intelsat where the operations were spun off into a private company and the international organization emerged with a new acronym and a new role supervising the private companies international treaty obligations.
I am pleased to confirm that the logo you have attached is indeed our "flag". I attach in two versions. Inmarsat had two different flags - which I will try to locate and send to you - "old logo" [shown here] is the one from 1979 up to around 1990. I will have to scan the interim logo and send it to you. If you need anything else, please let me know.