Modernist home of Britain's secret intelligence service

The MI6 building - a fortress-like cream and green structure, designed by the modernist architect Terry Farrell at Vauxhall Cross on the south bank of the Thames - is headquarters to one of Britain's most secret organisations.

The MI6 building - a fortress-like cream and green structure, designed by the modernist architect Terry Farrell at Vauxhall Cross on the south bank of the Thames - is headquarters to one of Britain's most secret organisations.

The Secret Intelligence Service (SIS) - the organisation's more correct title - was formed in 1921, when it was known as Military Intelligence, section six - or MI6 for short.

Throughout the Cold War the service's members were engaged in espionage and other intelligence activities abroad, using British agents and disaffected nationals of the countries in which they operated. It operates discreet out-stations in embassies and consulates around the world who locate and recruit agents.

The service, which is directly responsible to the Foreign Secretary, Robin Cook, and ultimately to the Prime Minister, has been busily redefining its role since the fall of the Berlin Wall, and is thought to co-operate closely with the domestic security service MI5 in keeping track of Irish terrorist groups and more recently in anti-drugs smuggling efforts.

The service is seen as a crucial part of the Whitehall machine and its information is used formulating foreign policy. It was criticised for failing to predict the Argentinian invasion of the Falklands and Saddam Hussein's incursion into Kuwait.

The work of the service has been romanticised in Ian Fleming's James Bond novels and the accompanying films, and ironically part of the building was shown being blown up by a bomb smuggled in by a terrorist in the last Bond film, The World is Not Enough. John Le Carre's Smiley books were also based on the work of M16

The hi-tech HQ building bristles with security features, including an extensive CCTV system, and bomb and bullet-proof walls and windows. Much of the complex is below street level to protect the most sensitive areas from terrorist attacks. Most of those who work there are civil servants who provide intelligence analysis for ministers.

The building project was severe criticised by MPs, after the cost of construction and fitting out over-ran original estimates and finally came out at many hundreds of millions of pounds.

Earlier this year, both MI6 and the domestic intelligence service were warned that their ability to gather intelligence could be compromised by recent security lapses.

The chairman of the Parliamentary Intelligence and Security Committee, Tom King, said informants, on whom the agencies relied for information, would dry up if they feared their covers could be blown due to weak internal security. His warning followed the disclosure that a laptop computer containing classified information had been mislaid by an MI6 officer - reportedly in a taxi cab.