On polling day I wanted to send a message to Blair. All I had to decide was who would be the postman ...
And so the deed is done. And the political postmortems are under way. So is my own postmortem as to how and why I voted as I did. Here's how it goes.

In Holborn and St Pancras Frank Dobson has been the MP since 1979. He became a figure of considerable political clout when he was made secretary of state for health in the first Blair government in 1997. Frank is a pugnacious politician and not one to toe the Blair line. He has a fine record of voting with the rebels on tuition fees, the Iraq war and the prevention of terrorism bill.

What's more, he is an attentive constituency MP. When I wrote asking him to vote against the bill that makes incitement of religious hatred an offence, he phoned to explain why he had no intention of doing so, and indeed was a prime supporter in the matter about which he feels very strongly. We then had a good discussion about the relative priorities of freedom of creative expression and the right of the Muslim community to enjoy freedom from abuse. We agreed to differ.

Dobson was out of the health department in 1999, and then suffered the humiliating manoeuvres that had him standing as the Labour candidate for mayor of London. He was thoroughly trounced by Ken Livingstone, and has since been a doughty backbencher with a voting record that I thoroughly support. Why then was I hesitating to vote for him?

Every constituency has its own dynamic, and those where the sitting MP has a huge majority presents its voters with different options from those where there is all to play for. Just so in Holborn and St Pancras. Dobson, I believed, would walk it. This freed me, a long-time Labour supporter, to consider other options. I was let off the hook of the gruesome role being spelled out for me by Labour's last-minute panic. Michael Howard would not be let in my back door. Why not use my vote to register not my disagreements with Dobson, which are few, but my disagreement with the Labour party, which are few, but crucial.

There are two issues which are a matter of principle for me. On one of them I earn, as he constantly reiterates, the respect of the prime minister. I strongly opposed the invasion of Iraq, and its re-emergence in the last week of campaigning lit up this drab election with some fine exchanges on radio and television, and some good journalism. My personal view, for what it's worth, is that Tony Blair is not a liar. He came to a view on Iraq as to what he believed was the right path and then sought to back it up by whatever means he could, including the manipulation of evidence and opinion to suit his cause. That's what politicians do. But I so passionately disagreed with his analysis of the world picture that I marched against the war and wanted to distance myself from the politics that took us there.

The other issue is the rule of law. It follows, of course, from the politics of the war, which in turn derive from the events of September 11. One thing leads remorselessly to another. Proposals to severely restrict the freedoms which characterise our democracy could well end up betraying the very ideals we proclaim we are fighting to support. The situation in Guantánamo, the proposed acceptance of evidence gained by torture abroad, and the case for arrest without trial are all matters that were once unthinkable in a civilised society - and they are now being thought. The unlovely phrase that covered my voting intentions was "sending a message" to Blair.

But who would be the postman? And indeed, given the safety of Dobson's seat, why did I bother to vote at all? I was brought up to think it was a duty, and have come to appreciate it as a right. So though it wouldn't matter in the final result, it would matter for me. I wanted to be part of the process; I want to share the talk, read and argue, consider and decide. I wanted to be up late fretting about the result.

I began to consider the other great issue of our times, that hasn't claimed the limelight as it should. It's a cause that needs supporting. It needs an MP or two in the house. The shape of politics is changing from the two-party rivalries of recent decades. It's clear parliament needs more diversity, more independent thinking. So in the end I voted to offer them encouragement. I voted for the Green party.