Most people worldwide who have at least a cursory interest in spying and espionage, are familiar with the names MI5 and MI6. And those who have more than a casual interest in the intelligence world are aware that MI5 is the UK’s internal counter-espionage and counter-intelligence service while MI6 is Britain’s foreign intelligence collecting and spying agency.

Only they’re not!

If you’re an employee of MI5 or MI6 then nowhere on your pay check or any reference to your designation, job title or status within these organisations would the names ‘MI5’ or ‘MI6’ crop up. People working in either rarely if ever call them by the now legendary, iconic titles that the general public, spy fiction authors (including myself) and the media always refer to them as.

How come? I hear you ask while scratching your head.

The answer is twofold. One lies with the early history of the two services and the second reason is because for the bulk of their history neither organisation had any above ground status: in other words they didn’t officially exist.

Against a background of near hysteria whipped up by the popular media about German spies and espionage against British military installations prior to the First World War, the government established a Secret Service Bureau in 1909. It was placed under the control of the then War Office. Very quickly, the original Bureau split into two sections: one focused on countering espionage which eventually became MI5 while the other concentrated on foreign intelligence gathering and would become MI6.

When war broke out in 1914, both agencies were subsumed within the military intelligence directorates and were assigned the departmental names ‘5’ and ‘6’ which they have been known to the world as ever since.

However, after the war and a tussle between Whitehall departments, the police and the military, both services were effectively civilianised, i.e. severed from any control by the military (who still retained their own intelligence arms), though still, in theory working in close co-ordination with them.

MI5 (after fighting off an attempt to be ‘amalgamated’ with the Metropolitan Police Special Branch) became the Security Service, in theory under the supervision of the Home Office. Meanwhile, MI6 became the Secret Intelligence Service (SIS), again in theory subordinate to the Foreign Office.

I say, ‘in theory’, because in reality this control was only nominal and amounted to both being symbolically answerable to the Home or Foreign secretaries respectively. Apart from that, neither service had any official existence, and therefore had no effective legal status. MI5 and MI6 were laws unto themselves.

In a world in which from its inception the CIA were responsible to Congress committees and had a high public profile and where even the Soviet KGB, for all its sinister reputation, was an official state entity and also had a high profile with the Soviet public, until almost the last decade of the 20th century neither MI5 or MI6 were ever referred to by any government (of whichever political hue) and had no legal status whatsoever.

 Today, whenever a news story breaks out concerning British intelligence the BBC will park a TV news crew in front of MI5’s Thames House HQ in Millbank or beside the imposing façade of MI6’s iconic offices in Vauxhall. Thirty years ago this would have been effectively prohibited. Only a few radical, dissenting media outlets would dared have revealed the whereabouts of the UKs intelligence agencies.

It was in this twilight zone that journalists, academics and those interested in them continued to refer to Britain’s intelligence services by their old wartime names of MI5 and MI6 as neither the titles Security Service or Secret Intelligence Service had any official status and would never be acknowledged by government sources.

And in the gap created by official denials, thriller writers and filmmakers lent an almost mystical allure and glamour to what had been grey military department titles and the names MI5 and MI6 became enshrined in the popular psyche and quintessentially British.

Of course, in the internet age such deniability would be absurd. But even before then the cracks in the British Government’s attempts to conceal and deny the existence of its own intelligence agencies were becoming more glaring.

It all came to a head in the mid-1980s with the trial of the Spycatcher author Peter Wright. These were the colourful memoirs of former MI5 officer Wright and apart from claims of right-wing plots by elements in MI5 against the British Labour governments of Harold Wilson, Wright also memorably wrote about how he and his MI5 colleagues “..bugged and burgled our way across London at the state’s behest.”  In spite of its many inaccuracies, the book’s publication, the attempts by the British government to ban it and the subsequent trial were media sensations and backfired spectacularly on the government.

The result was the government resolved to place both agencies on a firm legal foundation. This was enacted with MI5 by the Security Service Act of 1989 and with MI6 though the Intelligence Services Act of 1994. Now both services have an official and legal existence.

But in spite of this new found legal footing the names MI5 and MI6 have virtually become a brand emblematic of deception, skulduggery and, yes, adventure, so much so that both the Security Service and SIS capitalise on this by calling their official websites MI5 and MI6 (the only situation where they do so; as mentioned in all other circumstances they revert to their authorised titles).

What began as a typically British obsession with secrecy has become an international trademark that transcends the mundane reality of intelligence work.

What’s in a name indeed!