I think that may be correct. The IMO is one of those quasi-governmental things, and INMARSAT seems to be a spin off or the IMO. The IMO is headquartered in London, because that’s where international shipping insurance is centered, and people trust England’s reputation for seamanship and fairness, compared to other possible locations.
I appears that INMARSAT worked with some very capable people in the British transportation safety agencies to analyze the satellite data, and I personally find their conclusions plausible, prima facie. I’d need to know a lot more to judge for sure. I think because of the political and diplomatic implications, both organizations are remaining very tight lipped. Good for them, in the US everyone involved would be eating lunch at expensive restaurants and blabbing to reporters.
Something smells in all this...