Daniel Craig’s first job as James Bond in the film Casino Royale was to fly to Prague to kill a renegade MI6 officer. Having thus earned his 007 designation and the much vaunted licence to kill, he went on to gun down a dozen prison guards in Madagascar while hunting a terrorist bomb-maker.

It must have come as something of a surprise to him last week, then, to learn that MI6 hasn’t killed anyone for years. Sir Richard Dearlove, the former MI6 chief, told the inquest into the death of Diana, Princess of Wales that, contrary to claims from two separate whistleblowers – David Shayler, who said the service had drawn up a plan to kill Colonel Gadaffi, and Richard Tomlinson, who described a plot to kill Slobodan Milosevic – the service had not carried out any assassinations since he joined it in 1966.

Technically, under the Intelligence Services Act, the real James Bonds could commit any crime outside the UK, be it murder or bigamy, if it were authorised by the foreign secretary. However, while Dearlove conceded that there had once been a plan drawn up to kill a Balkans war criminal, the officer responsible was apparently rapped over the knuckles and told never to think such nasty thoughts again.

Really? Whatever happened to that licence to kill? Do Britain’s enemies now hand over their secrets to MI6 so easily that our spies never have to kill anyone? Of course, we always knew that Bond himself was a fictional character. But Ian Fleming was a wartime intelligence officer with close links to MI6. Surely he couldn’t have made it all up?

No, he didn’t. In fact, a surprising amount of the Bond story was true. The first “C”, as the head of MI6 is known, was Mansfield Smith-Cumming who – like Bond – was a Royal Navy commander when he started his new career. Cumming, whose name was shortened to C to protect his identity, was a particularly tough bird. Trapped by his car after it ran into a tree in wartime France, he hacked off his leg with a penknife in an attempt to save his dying son.

Compton Mackenzie, a secret service officer during the first world war, described how Cumming gave him the swordstick he had taken with him on spying expeditions to Germany before the war. “That’s when this business was really amusing,” Cumming told him. “After the war is over, we’ll do some amusing secret service work together. It’s capital sport.”

It was the system put in place after the first world war that gave rise to the “double O” designation of officers. The first two digits represented the country in which the officer was working, with the station chief taking 24000 and his lead agent-runner 24001, and any others becoming 24002 and so on. On a number of occasions these officers did not just carry a gun but actually used it.

At the end of the second world war MI6 absorbed the remnants of the Special Operations Executive, the wartime organisation that, on Churchill’s orders to “set Europe ablaze”, had wreaked havoc behind enemy lines. Some of the darker elements of that organisation sought not just to gather intelligence on Britain’s enemies but also to undermine them and even to bring down their leaders.

These dubious activities reached their height during the 1950s when George Kennedy Young, the most enthusiastic of these so-called “robber barons”, masterminded the coup that ousted Mohammed Mossadeq, the Iranian prime minister, and the plot to “bump off” Gamal Abdel Nasser, the Egyptian president. A number of plans were put together variously involving an exploding electric shaver, poisoned gas in the ventilation system or a straightforward hit squad.

Despite the apparent backing of Anthony Eden, the prime minister, nothing happened – and shortly afterwards the robber barons were dethroned and MI6 started to concentrate on gathering intelligence. During the cold war, agents ceased to carry guns but started using so-called “contractors” to mount a number of missions inside the Warsaw Pact countries and elsewhere, most notably Afghanistan. These contractors were sometimes special forces who were briefly “retired” to mount the operations or former special forces working in private security who were brought in to do individual jobs.

Inevitably they found themselves drawn into gun battles and had to kill or be killed, but technically they were not MI6 officers so Dearlove’s evidence was correct.

During the Balkan wars, MI6 officers began to get out on the ground themselves, usually under cover as civil advisers to the military, collecting intelligence and setting up links with the various factions that would lead to occasional efforts to broker a local peace deal.

Richard Tomlinson, a renegade MI6 officer, claims it was during this period that a plot was hatched to kill Slobodan Milosevic, the Serbian leader. The plan involved shining a blinding light at his car as it passed through a tunnel in Geneva, which would cause it to crash.

Since Diana’s death, witnesses have said they saw a blinding flash in the tunnel under the Pont d’Alma in Paris just before her car crashed – testimony that has fed the conspiracy theories aired by Mohamed al-Fayed at the inquest last week.

Dearlove himself admitted that an officer, known only as A, had drawn up such a plan, but said that its intended target was not Milosevic but another – as yet unnamed – Balkan political figure. Officer A, whose short-lived plan it was, will give evidence to the inquest next week, along with eight other equally anonymous serving or former MI6 officers.

Their current close links to the military mean that MI6 officers have no need to carry out any “dirty work” themselves, even if they sometimes carry guns for their own safety.

When the allies invaded Iraq, MI6 had already set up a network of agents inside the southern city of Basra. In tandem with the Special Boat Service (SBS), it devised a number of innovative ways of collecting the intelligence. While British troops waited south of the city for the right moment to attack, SBS commandos in civilian clothes and driving 4x4 vehicles went into the city with an MI6 operative, dragging their sources off the street as if they had been arrested by Saddam’s security forces.

MI6 still works closely with the SAS in Iraq and in Afghanistan, where it has been behind attempts to split off local Taliban leaders in Helmand province from the organisation’s Pakistan-based leadership.

As a safeguard against the dangers of the post9/11 era, a small team of former special forces – mostly ex-SBS but also ex-SAS and Royal Military Police close protection experts – have been employed to provide protection for MI6 officers. Initially brought in on expensive contracts that saw them paid a daily rate, they have since been taken on as salaried members of MI6.

Given their role, it goes without saying that they could be called on at any time to shoot to kill – and may well have already done so. But no one is talking about it.

Michael Smith is author of The Spying Game, published by Politico’s. He is writing an unofficial history of MI6

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