Angus McKinnon is a maritime investigator.
When a ship sinks or gets seriously damaged and there are insurance claims to be checked out before monies are exchanged, it falls to people like McKinnon to head to the scene and discover as best as possible who is responsible. He is very good at it and has been so for quite a few years making him an experienced detective respected in the industry. He works largely for the Caledonian Marine Mutual P&I Association, known in the industry as CMM and is their "correspondent in the East Med".
He also takes the odd job here and there, now and then, for the International Maritime Task Force (IMTF) which is "a shady offshoot of what was once British Naval Intelligence and was now merged into the Ministry of Defence's Intelligence Department". According to McKinnon, the IMTF "had been set up as a taskforce to investigate the spate of maritime fraud incidents which reached epidemic proportions in the seventies. Its success in getting to the route of these crimes ensured the IMTF’s future. Before long they were supplying various EU and NATO naval organisations with intelligence relating to the flood of piracy attacks in and around the Gulf of Aden. It suited the IMTF’s masters in the Ministry of Defence to retain its taskforce status. It allowed for greater flexibility and less accountability."
So while the CMM is McKinnon's true employer, many of the assignments he goes on are at the behest of the IMTF. While McKinnon might not think of himself as a government agent, it would be safe to say that others might, and do.