On this issue I am ready to take to the streets

Just two days of debate are all that may lie between us and the loss of 300 years of liberty

Suppose that by the time the House of Commons has completed its work on the Prevention of Terrorism Bill later today, it still gives legal form to indefinite house arrest without trial on the say-so of a government minister. What shall we do then? I mean those of us who believe that the 800-year-old right of habeas corpus - thou shall have the person in court - should not be given up.

Let me speak for myself: I live in central London, I travel by Tube, I make regular trips to Paris via the Channel Tunnel, I use airlines. I am a citizen of a country that invaded Iraq. I am vulnerable. Nonetheless, I would rather go on running the daily risk of being injured or killed in a terrorist incident than have my freedom from arrest without trial removed.

Don't tell me that bringing in a judge to look over the Home Secretary's shoulder a few days after a control order has been issued restores the situation. Prisoners still wouldn't know the nature of the charges against them nor the evidence upon which they were based.

Doesn't it seem extraordinary that one must need make these simple points about a free society in a newspaper article in 2005? Brian Sedgemore, a Labour MP who opposes the measure, put it very well in the House of Commons last week: "Many Members have gone nap on the matter. They voted, first, to abolish trial by jury in less serious cases; secondly, to abolish trial by jury in more serious cases; thirdly, to approve an unlawful war; fourthly, to create a gulag at Belmarsh; and fifthly, to lock up innocent people in their homes. It is truly terrifying to imagine what those Members of Parliament will vote for next. I can describe all that only as New Labour's descent into hell."

Precisely. That is the problem and that is why I ask: what are we to do? By the end of today, then, we may have only the House of Lords to defend our freedoms. Should we content ourselves with waiting to see what their Lordships decide to do, switching on the radio or television news a bit anxiously to hear how the debate is going, or picking up the next morning's newspaper with a fair degree of trepidation?

When one remembers that earlier generations went to war to defend our freedoms, this is a feeble response. Again I turn to Brian Sedgemore: "I am reminded that our fathers fought and died for liberty - my own father literally - believing that these things should not happen here, and we would never allow them to happen here."

This looks to me like an occasion when, for the first in my life, I must go on to the street in protest - or at least I must stand outside the House of Lords as it examines the obnoxious bill. I shall hope that others will be there, and that there will be a spontaneous combustion of protest against the most authoritarian government that Britain has seen in modern times

For this reason, I was very encouraged by the report on one newspaper yesterdaythat hundreds of leading figures from the arts, law and the church had signed a declaration accusing the Prime Minister, Mr Blair, of violating precious British values.

It listed among its signatories such disparate figures as Vanessa Redgrave and Frederick Forsyth, Sir David Hare and Mr Scruff, the DJ, as well as a long list of eminent lawyers. Its statement concluded by asserting that: "Visible injustice debases our democracy and undermines our safety. Indefinite detention without trial is always wrong. We call on our politicians to think again."

Good, but assuming the Government gets its way today in the Commons, I urge the signatories to go one step further and stand outside the House of Lords tomorrow when it stages a second reading debate and then again two days later, on Thursday, when the Lords examine the Bill line by line. Just these two days of debate are all that may lie between us and the loss of safeguards we have enjoyed for 300 years.

"When the people come out onto the streets, it is always important." That was said to me by Neal Ascherson, the wise Scottish author who used to write a column for the Independent on Sunday. I had been speaking to him about the great crowds that had gone to Kensington Palace to mourn the death of Diana, Princess of Wales. That did indeed turn out to be important because by their homage and later by their attendance at the funeral procession, the British people rebuked the Royal Family.

Before that, in recent memory, there were the poll tax riots, and subsequently the great peace march, one million strong, that silently passed through London streets to protest against the decision to invade Iraq. "Not in our name" was written on the banners.

What should we write on the banners this time? "No police state" goes too far. "No house arrest" or "no detention without trial" - they would both do. But on further consideration, I think that "not in our names" still has strength. If Parliament gives David Blunkett, the Home Secretary, the powers he has requested, it will not have been in my name. I shall look through the lists of those who voted in favour and shudder.