On Monday I was formally expelled from the Labour Party. Of course, I recognised this would be an inevitable consequence of my decision to run as an independent candidate for London mayor. But I do not think that anyone who has not spent more than 30 years of their life at every level of that party can imagine the painful wrench that was involved.
The expulsion announcement was expected, but not pleasant. I joined the Labour Party in the Sixties, when many left-wingers were leaving, because I have never seen politics as being about abstract principles or protests, but about having the practical power to change society for the better.
To be capable of winning and wielding power, Labour, like any great party, has to represent a broad coalition of interests and views. The Labour Party I joined was always that kind of very broad church. It was usually led by people on its right flank, but the left and centre also had a recognised place within the movement - including the opportunity to put their views and candidates to the test of a democratic vote.
The left didn't often hold the leadership, but it set the agenda in the party in a way that was denounced as outrageous leftism at the time, but became mainstream - and Government policy - a decade later. The GLC was just one example of that pattern.
It was on this basis that the party won its landslide electoral victories in 1945 and 1966, when our share of the vote was far higher than in 1997, when it was the collapse of the Tories that gave us such a large majority of seats.
A leader such as John Smith, for example, came from the right, had firm principles and was open and tolerant. When he disagreed with the left he did so openly and not via off-the-record briefings. I cannot remember one campaign of personal denigration he ever engaged in. One thing I will miss tremendously for as long as I am outside the party is the serious cut and thrust of debate with honest right-wingers with whom I differed on policy but united around the practical goal of winning and wielding political power.
What I will not miss is the tight-knit group of spin doctors and lobbyists who now occupy such influential positions and are trying to turn the Labour Party into some kind of narrow group in which all serious dissent is outlawed. These people have done enormous damage to the party.
They delight in treating the tens of thousands of loyal party workers, and the voters whose views they reflect, with open contempt. But as has been seen in Wales, Scotland and London, ordinary electors increasingly understand these people, who have no concept of loyalty. Their treatment of someone like Mo Mowlam is typical. Mo's only crime was to be the Government's most popular minister, exemplified when the very mention of her name by Tony Blair produced an ovation at the 1997 conference. From then on, Mo's card was marked and the hatchet men set to work with anonymous briefings, vile slanders about her health and every dirty trick in the book.
One of the least endearing characteristics of these petty bureaucrats is that whatever disasters their antics produce, somebody else is always to blame. Take the fiasco they have produced in London. No sooner had the first opinion poll appeared the day after the selection, than anonymous sources were briefing that Frank Dobson might be replaced at the last moment. Well, if Frank loses badly, I have little doubt that the people who are really responsible for this mess, the ones who decided to rig a ballot blatantly, will be busy telling journalists that the real problem was the candidate!
I am quite confident that sooner or later all of this is going to provoke a tremendous backlash both from the electorate and from Labour's hundreds of thousands of decent party members. Whether or not they agreed with my decision to stand as an independent, they will have understood why I felt compelled to make it. They, like most Londoners, will have no desire to prolong this conflict once the voters have delivered their verdict on 4 May, and they will understand that it was a narrow, intolerant group that produced an unnecessary and damaging result.
They certainly won't understand the logic of those who briefed the press yesterday that there could be no question of my being readmitted to the Labour Party for a minimum of five years. Nor will it be lost on them that those responsible for those briefings are the very people who have welcomed former leaders of the SDP back with open arms.
My "crime" was to refuse to accept a ballot which was blatantly rigged. I had no desire to damage the Labour Party as such - quite the reverse. The SDP, on the other hand, was a determined attempt to destroy the Labour Party, which in 1983 helped produce one of the party's worst-ever general election results.
Following the mayoral election, if elected, my intention will be build a good working relationship with Tony Blair. I will work for the best possible deal for London, and I'm sure, with a general election on the horizon, Labour will take the views of 5 million voters in London extremely seriously.