The arrival of the Burmese opposition leader Aung San Suu Kyi in Oslo today marks both the end and the beginning of an extraordinary journey. There can be no more powerful example in the world today of how quiet, persistent courage against all the odds can pay remarkable dividends, producing change which for many years seemed almost unthinkable. But not everything has changed. As Aung San Suu Kyi herself has rightly noted: "A little bit of scepticism is in order."

For more than two decades, Aung San Suu Kyi has responded to the repression of the ruling junta – including 15 years of house arrest and an apparent assassination attempt – with a quiet insistence that justice for her country must eventually be achieved. Now, the government has embarked on a reform programme which many thought would never come to pass. Credit must go to President Thein Sein, who may yet prove to be his country's FW de Klerk. Above all, credit goes to the serenely defiant Aung San Suu Kyi herself and the persistence of ordinary Burmese.

When photographer Tom Pilston and I travelled to Rangoon to interview Suu Kyi for The Independent 14 years ago, it proved one of the most memorable trips of my life. People were eager to talk and paralysed by fear. A student who spoke warmly about Aung San Suu Kyi broke off: "It's very difficult. Please forgive me. We are so afraid." A shopkeeper began a friendly conversation, then started trembling. With a sad bow, he asked me to leave: "Informers are everywhere."

Making contact with the "Chief Destructionist" (as the official media liked to describe her) was forbidden. It was unsurprising that, after our meeting, we were questioned, strip-searched and deported. "You can talk to anybody. But you can't talk to Aung San Suu Kyi. It is not permitted," said one of the officers. Because? "She disagrees with the government."

Aung San Suu Kyi worried aloud about the "brutality" that we would face when running into the arms of the waiting plainclothes intelligence agents. In reality, of course, we were treated with kid gloves. It is Aung San Suu Kyi and her compatriots who have faced the brutality for decades. Yet even after the lethal repression of the "saffron revolution", the huge and peaceful protests of 2007, the UN Security Council – in a pattern that has again become all too familiar – was eager to look away from the bloodshed.

When Aung San Suu Kyi was awarded the Nobel Peace Prize in 1991, she could not go to Oslo to receive it. She was still under house arrest, after her party had won 80 per cent of the seats in elections the previous year. Even as her husband Michael Aris was dying of cancer in 1999, she was unable to be with him. He was denied a visa to Burma; she knew that if she left the country, she would not be allowed to return.

The moment when she gives her belated Nobel acceptance speech in Oslo City Hall tomorrow is historic for Burma, reminding us how much has changed. Tomorrow's event also has significance for the wider world. Her arrival reminds us that astonishing battles can be won, even in circumstances where the pessimists have long since given up on change.

In Dublin on Monday night, she will receive Amnesty International's Ambassador of Conscience award at a concert where Bono and others will perform. Amnesty International announced the award in July 2009. Only the bravest optimist would have dared at that time to suggest that she would collect the award herself, as an elected member of the Burma parliament, less than three years later. Her trip to Britain next week, too, will include many moments of rejoicing. But this is no simple fairytale, for Burma or for Aung San Suu Kyi.

Political pressure remains important, to ensure that reform continues. Hundreds of political prisoners have been released. But hundreds more, including many prisoners of conscience, are still behind bars. Khin Kyi, to take just one example, is still serving a 15-year sentence. His crime: distributing the logo and message of a peaceful protest group, Generation Wave.

Nor is there any hint of the accountability that is badly needed for the crimes of past years. Amnesty International has repeatedly documented crimes against humanity in the conflict in the ethnic border areas. And yet abuses against ethnic Kachin civilians in the north have dramatically increased after the breakdown of a 17-year ceasefire.

These will be astonishing days to remember, as we see the impossible become real. But for Burma to become a country where the rights of all are respected, the journey has only begun.

Steve Crawshaw, a former foreign correspondent with 'The Independent', is Director of the Office of the Secretary General of Amnesty International

Adrian Hamilton returns next week