In her Dimbleby lecture in June, Stella Rimmington, the head of the security service, formerly known as MI5, said the process of reform in Russia was "still vulnerable". "Although a year or so ago the Russians reduced the number of their Intelligence Officers here, the total has now begun to creep up again," she said. "We must therefore remain on our guard."
It has been suggested that Mr Malikov is accused of counter-espionage on the part of the Russians - infiltrating Britain's own foreign intelligence services - rather than espionage of an economic or military nature, but the Home Office refused to give any details and Russian sources have denied suggestions that he was spying.
MI5 continues to devote about 20 per cent of its resources to countering Russian intelligence agencies. The Russians are understood to be recruiting a similar number of agents to that recruited in the Cold war. MI5 has no executive power to arrest peoplewhom they catch spying - that is for special Branch - but is in charge of amassing and collating evidence.
In a much more relaxed age, why should the Russians continue to pose any threat "to national security"? Recent events of interest to the Russians have been the first Trident submarine patrol, which left Faslane on the Clyde last month, and possibly events in Northern Ireland.
With the break-up of the Soviet Union, Russia's maintenance of a technological edge against competitors and potential adversaries, if anything, more dependent on technology acquired from abroad. In the 1940s and 50s Russia was able to develop nuclear weapons and intercontinental missiles much more quickly than the western powers because they took existing technologies.
Britain and Russia are also rivals in the international arms trade. The disintegration of the Soviet Union meant that Britain moved into second place as an international arms seller. Arms sales are one of Russia's principal sources of hard currency. Intelligence on British defence exports and future prospects would be of particular value to the Russians at the moment.Reuse content