The decision comes after what has been perceived as a remarkable development since the suicide bombings in London on July 7.

According to intelligence sources a significant number of applications for jobs through existing methods of recruiting had come from Muslim graduates, who said that they wanted to do something for their country.

They had applied through the only available outlet, a PO Box address on the Foreign and Commonwealth Office website. The unexpected rise in interest encouraged the hierarchy at Vauxhall Cross, the headquarters of the service by the Thames, to change its longstanding methods of recruiting and to tap into what appeared to be a rich vein of eager patriots.

Although there is no decision yet on how the service intends to make itself more open to those interested in a spying career, intelligence sources say that it aims to advertise in a way that would make it obvious that it was MI6 offering a job.

It will be a significant break from traditional recruiting practice, which has largely depended on talent-spotting by trusted university dons.

The only advertising deployed by MI6 until now has been so opaque that applicants arriving for initial interviews have had no idea who their potential employers might be.

They get an inkling only after they have been through several interviewing hoops, perceived to be necessary to ensure that only suitable applicants reach the stage where the details of a potential spying career are revealed.

Too much secrecy at the recruiting end of the game is now seen to be counterproductive. MI6’s sister service, MI5, across the Thames, has for many years been more transparent and runs its own website which includes job application forms.

However, MI6 has always treasured its secretiveness, arguing that as the focus of its work involves covert intelligence-gathering overseas, it has an obligation to its agents to remain in the shadows.

The development towards open advertising is expected to lead to a surge in applications from ethnic minorities and women, although the numbers are already high: in 2004-05, 9 per cent of new entrants were from ethnic minorities and 41 per cent were women.

Since the London bombings, the number of people applying to join MI6 through the PO Box number has risen by a fifth, many of whom referred to the attacks.

MI6 created the number — PO Box 1300 — in 1992 but started using it as a recruiting tool only in 2001. That in itself was a break in tradition, but only those who were aware of the existence of the number or found it by chance on the Foreign Office website applied by that route.

So the talent-spotting method, familiar to readers of the George Smiley spy novels of John Le Carré, reigned supreme.

It has not always had beneficial results. During and after the Second World War, a top talent scout of a different kind, at Cambridge University, recruited the infamous spy ring of undergraduates, including Harold “Kim” Philby, Guy Burgess and Donald Maclean who worked as double agents for the Soviet KGB.

IN THE SHADOWS

• The core of MI6’s operational or agent-running cadre is drawn from “high-calibre graduates with a commitment to public service who exhibit integrity, strong intellectual skills, strength of character and an interest in international affairs”
• Those with analytical skills, able to map out terrorist networks, linguists, particularly Arabic speakers, and computer specialists are also wanted
• All graduate entrants are expected to serve abroad as intelligence officers during their careers
• The starting salary for a 23-year-old agent is about £24,000
• Non-graduate entrants with two A levels work in support roles, but also serve abroad
• Candidates, who should be in their early 20s to early 30s, may include those bored with other careers
• About a quarter of the 2,000 staff serve as undercover intelligence officers in British embassies
• It can take up to six months to complete the vetting process
• Famous MI6 spies: David John Moore Cornwell (or John Le Carré), Graham Greene and Malcolm Muggeridge
• The model for James Bond: Sir Fitzroy Maclean

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