The spy exchange unfolding in Moscow, New York and points between evokes a bygone era when cold war teetered on the verge of hot, superpowers sniffed out each other's deadliest secrets, and the swaps even had a ringmaster in a dapper German communist.

Vladimir Bukovsky, a Russian freed in a 1976 exchange, expressed surprise yesterday at the Cold War rerun, saying trading prisoners should be a thing of the past.

"It's a bit sad that everything in the world seems to end up like a blind donkey going around in circles," the 67-year-old former Soviet dissident said in London.

But the parallels go only so far. Espionage's new wave does not quite measure up to the old.

Where the Kremlin's daring agents of earlier generations ferreted out atomic bomb blueprints and infiltrated Nato planning councils, the hapless 10 of 2010 are accused of foraging for White House "kitchen rumours" and US policy chatter.

And where the current swap candidates are obscure US suburbanites and ineffectual operatives, the trades of that earlier time involved notorious spymasters and celebrated political prisoners.

In the last of those headline-making swaps, in a divided Berlin on a grey Tuesday in February 24 years ago, one of the Soviet Union's best-known dissidents, Anatoly Shcharansky, emerged from nine years' imprisonment to walk across the snow-covered Glienicke Bridge to freedom - and eventually, as Natan Sharansky, to a life as an Israeli politician.

The human rights activist was part of a trade also involving five alleged Soviet-bloc spies and three Westerners held in the East.

During the 45-minute exchange on the green steel bridge over the Havel River, separating West Berlin from East Germany, a balding, bespectacled man in a stylish suit and a white Mercedes drove up from the eastern side and met the prisoners.

That affluent intermediary was the late Wolfgang Vogel, a lawyer from communist East Germany who over three decades was instrumental in brokering both spy swaps and the larger-scale exit of ordinary people from East Germany, in exchange for West German government payments.

Twenty-four years earlier, in 1962, Vogel had engineered an even more spectacular - and secret - swap on the same bridge: the exchange of US spy-plane pilot Francis Powers, shot down over the heart of the Soviet Union, for a Soviet spy known as Rudolf Abel, who for more than a decade posed as a New York artist while running an undercover ring of spies who passed on US atom-bomb secrets.

Over the years, Vogel was the go-between for the exchange of more than 150 spies and alleged spies. In 1985, the year before Shcharansky's release, he negotiated a mass swap of 23 alleged spies held by his own government for four East German agents convicted in the US

Through the decades of Cold War, through the ups and downs of detente and crisis, such prisoner exchanges became almost routine.

In 1964, at West Berlin's Heerstrasse crossing to East Germany, British businessman Greville Maynard Wynne, who was at the heart of a sensational Moscow spy case, was exchanged for Konon Trofimovich Molody, whose spy ring had collected data on British submarines.

Wynne was the conduit for Oleg Penkovsky, a key Russian agent for Britain's MI6 who later was executed.

When Bukovsky was released in 1976 and flown in handcuffs to Switzerland, it was in exchange for Chilean communist leader Luis Corvalan, imprisoned by dictator General Augusto Pinochet after Chile's right-wing military coup of 1973.

In 1981, in another Vogel-engineered deal, West Germany released convicted East German spy Guenter Guillaume in exchange for eight captured West German, American and British spies.

The lopsided nature of that trade pointed up Guillaume's importance: As a top aide to West German Chancellor Willy Brandt, he had purloined documents relating to the Nato alliance's nuclear strategy. Brandt resigned because of the scandal.

The collapse two decades ago of the Berlin Wall, the Soviet Union and the entire Cold War ushered in a time of East-West unity in Europe, friendlier US-Russian ties and, until now, a scarcity of old-fashioned spy swaps.

But although swaps are fewer, the spying goes on - to obtain confidential information about diplomatic moves, trade negotiations, advanced technology and other economic and political areas, as well as the traditional defence intelligence.

Soon after the Soviet Union disintegrated, the newly branded Russian Intelligence Service established an economic intelligence unit to study US economic policy via publicly available databases and "traditional intelligence methods" - that is, spies.

"Everybody steals everybody's secrets," spokesman Yuri Kobaladze said at the time. "There are friendly states, but not friendly intelligence services."