Throw the word "tempest" into a conversation with a bunch of forty-somethings and you're likely to evoke fond childhood memories of square-jawed hero Troy Tempest in that classic 1967 Gerry Anderson puppet series, "Stingray". Fast forward almost 40 years into the 21st Century and the word takes on an altogether more sinister meaning in the shadowy world of espionage.

The acronym "TEMPEST" has many interpretations, but the most widely accepted one is "Telecommunications Electronics Material Protected from Emanating Spurious Transmissions". It refers to the measures that need to be put in place to counter the interception of electromagnetic radiation being emitted from everyday apparatus such as hard drives, printers, fax machines, computer monitors and so on.

These emissions can be intercepted by covert agents and used to spy on an individual or organisation. For example, the radiation fields surrounding a seemingly innocuous CRT display may be picked up by rogue operatives, the signals demodulated and then, amazingly, the data that was originally displayed on the computer monitor can be pieced back together again.

Surely, you think, corporations and governments must be aware of this. But if so, what are they doing about it? The race is on to develop materials and equipment to counter this electronic surveillance activity. The methods may involve modifying power supplies and cables and shielding rooms and even whole buildings against "TEMPEST" attack.

If not good old Troy Tempest, who's coming to the rescue? Enter the UK Defence Evaluation and Research Agency (DERA) - the Government's key Ministry of Defence (MoD) research and development body.

In 2001, DERA was split into two parts: DSTL and QinetiQ. DSTL, the Defence Science and Technology Laboratory network, represents the most secretive MoD laboratories and test facilities, like the Chemical and Biological Warfare Research Lab at Porton Down and the Forensic Explosives Lab (among other things) at Fort Halstead, Kent, which are still under strict MoD control.

QinetiQ - a play on the word "kinetic" in the style of "quality" - is the commercial public sector wing of the old DERA facilities, bringing together the best UK scientific minds and using their cutting edge research in the wider industrial arena.

QinetiQ Aquila, at the end of typical residential Golf Road in Bickley, Bromley (below), is a comparatively little known former DERA site in the south east London commuter belt on the edge of Kent. It has been researching, developing and testing "TEMPEST" technology since at least the mid-1980s. Other activities there have included the test, evaluation and calibration of electronic components for inclusion in military defence projects.