I’ve spent much of the past 20 years living in or reporting on the former communist countries of Eastern Europe. Nowadays, with Budapest, Prague and Warsaw two hours away by budget airline, it’s hard to imagine that before 1989, half a continent was imprisoned behind landmines and barbed wire, its citizens terrorised by secret police, intentionally ground down by the endless, intrusive demands of the one-party state.

I saw those borders torn down, democracies arise and the basic freedoms that we take for granted — speech, movement and public protest — enthusiastically embraced.

Twenty years ago today the world witnessed the power of the crowd. Hungary’s reformist communist Government permitted the pan-European picnic near the city of Sopron, on the border with Austria, as a symbol of its commitment to a united Europe. The border was to be opened so that about 100 dignitaries and officially approved picnickers could cross freely back and forth. But Hungary was crowded with thousands of East Germans desperate to escape to the West. Many camped near the site of the picnic, waiting for the crucial moment. When the border was opened at three o’clock they surged forward. The guards did not open fire. They stepped back and allowed the East Germans to break through.

This, not the opening of the Berlin Wall in November, was the tipping point. August 19, 1989, accelerated a chain of events that brought down communism and the Soviet Union itself. Such is the power of the crowd.

After 1989 Big Brother was no longer welcome in Budapest, Prague or Warsaw — he moved to London to be ever more warmly embraced by successive Labour administrations. The birthplace of political liberties, the home of the Magna Carta, is now one of the most intrusive democracies in the world. Labour governments have introduced surveillance and monitoring systems of which the communists could only dream. Of course, Britain is not a real police state. But it is certainly sliding further into authoritarianism.

Perhaps because I live abroad, each time I return home I can clearly see quite how subtle and dangerous a process is unfolding. A series of Home Secretaries have presided over a steady, stealthy shredding of our civil liberties. I am amazed at how supine citizens allow local and national government to intrude ever further into their daily lives, logging, tracking and recording everything from household waste disposal to mobile telephone use.

These small changes seem to herald a more dramatic constitutional shift: the rewriting of the social contract under which citizens are apparently regarded not as active participants in society, but, at best as irritants to be monitored, and at worst as potential criminals to be pre-emptively arrested, just as George Orwell predicted in Nineteen Eighty-Four.

The phrase Big Brother has entered common parlance. But Orwell’s book was published in 1949 as communist regimes in Eastern Europe cemented their control through “salami tactics”. These were invented by Matyas Rakosi, Hungary’s communist leader from 1948-56. He sliced away freedoms sliver by sliver, until he established one of the most feared dictatorships in Eastern Europe. When the communists took over a town, for example, they did not appoint the mayor, but a deputy, to work behind the scenes and stealthily take control of the police and municipal administration.

In my more cynical moments I imagine Labour ministers following a similar methodology. They would never say openly: “We intend to criminalise public protest; to grant sweeping blanket powers of arrest to the police and change the very foundation of law, making citizens prove their innocence, rather than have the police and judiciary prove their guilt while demonstrating.”

Nor would they say: “We intend to privatise formerly public spaces and hand over state functions of public order to armies of unaccountable security guards.” Instead, changes are introduced stealthily, rarely debated by Parliament and are nodded through with the acquiescence of the Opposition, in the name of that useful catch-all “security”.

Whether by design or not, that seems to me to be happening.

Security is an issue. Communist regimes sought control for its own sake, to preserve their monopolies of power. The Labour Government has had to respond to a new wave of terrorism, perpetrated by British citizens who use the internet and covert communication techniques.

Preventing further terrorist attacks is part of a government’s duty. But preventing government from intruding too far into our daily lives is our duty — one we have so far singularly failed to carry out.

In the communist era Hungarians, Czechs and Poles looked to Britain as a beacon of fairness. After 1989 our Parliament, judiciary and free press were models for them. The former one-party states are now vibrant democracies. Despite corruption and a sometimes prickly nationalism, most of the new EU members can be proud of their transformation into modern civic societies.

While our freedoms wither, theirs flourish. It’s a common sight to see far-right demonstrators in front of the Hungarian parliament, hurling abuse and calling for the resignation of the Government. The police watch, nobody is arrested and everyone goes home peacefully. And when the police do use force, there is a vigorous national debate about balancing the right to protest and public security.

Twenty years after the collapse of communism, Eastern Europe is showing us what freedom means. At last, there are signs that we are waking finally from our stupor. in 1989 the East Germans camped on the Hungarian-Austrian frontier showed the world the power of the crowd. So take to the streets, people. While you still can.