Secret dead-drops by park benches. Discreet liaisons at the newsagent’s window. Brief cases swapped under the linen tablecloths of Pall Mall gentlemen's clubs. Spies do it best when no-one knows.

Advertising is the exact opposite, which is why the Government’s eavesdroppers at GCHQ have come out from behind their formidable wall of secrecy to plaster the streets of east London with their message.

The recruitment effort is the brainchild of HR consultancy, Penna, which was hired by the intelligence agency and came up with the “GCH-Who? Technical Opportunities ” slogan.

As the war against terror increasingly going into cyberspace, the spy centre is looking to find bearded Tech City patriots to join the Establishment and the war on terror.

Unlike most of the daubings in the hipster capital of Shoreditch , the adverts used “reverse” grafitti in which a pressure washer and a stencil are used to wash away street dirt create the temporary slogan.

The adverts come as it was announced that more staff are to be recruited for Government Communications Headquarter (GCHQ) in Cheltenham as well as the other two intelligence and security agencies, MI5 - the Security Service - and MI6, the Secret Intelligence Service.

A GCHQ spokesman said: “GCHQ is always looking to widen our recruitment focus to reach the people we would like to recruit and therefore we use a range of innovative channels for our advertising.

“We look at areas which are likely to contain a high proportion of people who we would like to recruit, in this case people with technical skills and experience.”

Flip-flop coders need not worry about James Bond levels of style. Jeans, shorts and T-shirts with counter-culture slogans are all seen around GCHQ which, to a hipster eye, is built in the shape of a cronut. Although mobile phones are a no-no so candy stays uncrushed during earwigging hours.