Mr Krenz, a sprightly 82-year-old, is in finer fettle than the country he once ran. The German Democratic Republic - East Germany - no longer exists. Thirty years after the tumultuous events of 1989 and the fall of the Berlin Wall, Mr Krenz has agreed to meet me.

For many years he was seen as the "young prince" - the successor-in-waiting to veteran East German leader Erich Honecker.

But by the time he replaced Honecker in October 1989, the ruling party was losing its grip on power.

A week before the Berlin Wall came down, Mr Krenz flew to Moscow for urgent talks with Soviet leader Mikhail Gorbachev.

"Gorbachev told me the people of the Soviet Union view East Germans as their brothers," he said.

"At the time I thought Gorbachev was sincere. That was my mistake."

Do you feel the Soviet Union betrayed you? I ask.

"Yes."

On 9 November 1989 the Berlin Wall fell. Crowds of ecstatic East Germans poured across the open border.

"It was the worst night of my life," Mr Krenz recalls. "I wouldn't want to experience that again. When politicians in the West say it was a celebration of the people, I understand that. But I shouldered all responsibility. At such an emotionally charged moment, if anyone had been killed that night, we could have been sucked into a military conflict between major powers."

Egon Krenz still takes an interest in politics. And still supports Moscow.

"After weak presidents like Gorbachev and Yeltsin, it is a great fortune for Russia that it has [President Vladimir] Putin."

He insists the Cold War never ended, but instead is "being fought now with different methods".

When we get out of the car in the centre of Berlin, a history teacher and his group of 10th graders come up to us. It's their lucky day.

"We're on a school trip from Hamburg to study the history of the GDR," the teacher tells Mr Krenz. "It's amazing to have you as a living witness. What was it like for you when the Wall fell?"

"It was no carnival," declares Mr Krenz. "It was a very dramatic night."