I explain this in detail about every three years, but it is plain from my twitter stream today I have made no significant inroads into public consciousness.

MI6 officers, when operating abroad, do so 99% of the time disguised as British diplomats. They serve three or four year postings like other Embassy staff and will have a “cover job” doing something else in the Embassy. Back home in the UK their “cover job” is working in the FCO.

A proportion of them will be “declared” to their host country, including the Head of Station, and operate in liaison with the host intelligence services. A portion will be “undeclared” and spy on the hosts themselves or on others in territory without the hosts’ knowledge.

Those are MI6 officers, British career spies. The great advantage of the Embassy cover is that they have diplomatic immunity and when they mess up and get caught, they are simply expelled.

“Agents” are not “officers”. In MI6 terminology “agent” is another word for “informant”. The fictional James Bond is not in fact a “secret agent”. He is an officer.

Agents are usually nationals of the host country, but not always. They are “recruited” and “run” by MI6 officers. Motives vary but in the large majority of cases agents provide information for cash. British people who provide information to the Embassy from motives of patriotism will usually do so to a normal diplomat and not to MI6, but British people can be recruited as agents for MI6, in situations where the information being provided is in some sense deeply secret.

Agents of course run far greater risks than the actual MI6 officers and do not have diplomatic immunity.

Matthew Hedges is not an MI6 officer. His research would be of interest to the UK authorities, and it is not impossible MI6 were running him as an agent, but it is much more likely he would simply be cultivated by a normal member of Embassy staff, if at all, or by the FCO in London.

I am obliged to say that Jeremy Hunt has done very well in the Matthew Hedges case. He has been prepared to take individual injustice for a British person much more robustly than we have generally seen from British ministers. I quite accept this is British exceptionalism and that Palmerstonian “Cives Romanus Sum” stuff is safe ground for a Tory minister. I do realise that Hunt is not exactly forthcoming about the human rights of jailed non-British activists and opposition figures in the UAE and elsewhere. But nonetheless Hunt has been unusually robust and done well in this instance.

I compare this to Jack Straw’s utterly disgraceful behaviour in the case of Sandy Mitchell and two companions fitted up by the Saudis over a terrorist bombing 20 years ago. Straw took the opposite view to Hunt and, in the interest of Saudi/British relations, made virtually no protest even though the men suffered dreadful physical tortures in prison.

Incredibly, when after release the victims sought to sue Saudi Arabia for compensation for the torture, through the British legal system, the New Labour government actually intervened in the court case – on behalf of Saudi Arabia.