"Only ten days till Tony’s election and people keep asking me about this Alastair Campbell blogger smartarse. Even TB thinks I’m trying to upstage his own campaign diary. Can’t even send an e-mail without messing up so why would I bother with a bloody blog?"

Well the fact is, he wouldn’t, so I did instead. I am Alastair Campbell, not the real one of course, but his proxy weblogger, keeper of his online diary.

Thousands of people have read it in the past few weeks, tens of thousands in fact, and quite a few (including a nice man from the BBC) have e-mailed me asking if I am for real.

Yet Campbell and I could not be more different. He’s a 47-year-old journalist-turned-spin doctor; I’m a 30-year-old who works in the marketing department of an online bookmakers. He is obsessed with politics; I have never even voted. He’s a man; I’m a woman. The only thing we have in common is our initials: AC.

I first came across "proxy blogging" on Tim Ireland’s Bloggerheads site, which encourages people to set up websites on behalf of their MPs. My own local member in Bethnal Green and Bow, Oona King, was tempting – but I thought I could have more fun closer to the seat of power.

I’d read Peter Oborne’s excellent Campbell biography, New Labour and the Rise of the Media Class, some years ago and had always admired the man’s combative attitude. The fact that he had been brought out of retirement to help run Labour’s campaign for a third term decided it and in early February I signed up at Blogger.com. I was up and running in minutes; now I just had to work out what to write.

I had a stroke of luck a few days later with the leaking of the infamous BlackBerry e-mail sent by mistake to Newsnight (the one where he advised the BBC’s finest to ignore the Flying Pigs posters and "f*** off and cover something important, you t***ts.") This was my Rosetta Stone, if you like, and from it I was able to get a feeling for Campbell’s prose style. He strips the language down to its bare bones, then chucks in a few swear words.

It also transpired that he doesn’t spell too well at speed, but I hate spelling mistakes and decided against copying that. I have had to live with complaints about his swearing.

Beyond that, being an online identity thief is easy. Oborne’s book gave me personal nuggets and a daily web search filled in most of the the rest.

Popbitch, the celebrity gossip messageboard, has been vital. When someone spotted AC out jogging in Kings Cross plugged into an iPod, that went in. That’s also where I found out how badly he had done on Who Wants To Be A Millionaire before the show was broadcast.

And some of it, I confess, I just made up, like his rantings about Piers Morgan or attacks on Michael Howard or Charles Kennedy.

I have no idea whether it was Campbell who persuaded Alex Ferguson to sign off a piece he supposedly wrote for Tony Blair’s online campaign diary, but it doesn’t require much of a leap of imagination to assume that he did.

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